Difference between SharePoint 2010 Search and SharePoint 2013 Search

Recently, I got an opportunity to configure Search in SharePoint 2013. Then I thought let me compare the difference between SharePoint 2010 and SharePoint 2013 search and then go for the SharePoint 2013 configuration.

Below are the some of the differences found during the analysis.

Sl.No.	SharePoint 2010	SharePoint 2013
1	Majority of the search runs under MSSearch.exe process	Only crawl component run under MSSearch.exe process. Rest of the search components run under SharePoint Search Host Controller Service i.e. hostcontrollerservice.exe
2	During crawl, as items are indexed (built-in Memory), they are streamed/propagated to a Query server and index there.	During crawl, crawled items are sent over to the Content Processing Component for further processing.
3	Crawl freshness is poor compared to 2013 search. E.g. In SharePoint 2010 it is easy to get into state where a very long incremental crawl would overlap into the next scheduled incremental crawl. This usually occurs because lots of security changes are being processed.	SharePoint 2013 improves the crawl freshness tremendously using Continuous and Cleanup crawl.
4	In SharePoint 2010 search, crawl component is ultimately responsible for extracting metadata, links and property mappings.	In SharePoint 2013 search, the Content Processing Component performs the document parsing, metadata extraction, links and property mapping.
5	In SharePoint 2010, the web analytics service application is responsible for analytics processing.	All analytics processing is performed by the Analytics Processing Component within Search Service Application.
6	Whenever document is changed/updated, the entire document will be re-indexed and propagated to query server.	The index is more efficient in SharePoint 2013 search. Because it’s been broken into update groups. A single crawled document could be indexed across several different update groups. Each update groups contains a unique portion of the index. This allows for partial updates which means if I make a changes to a document, only that change is updated within the index of the associated update group instead of entire document.
7	Query runs under MSSearch.exe and retrieves properties from the Property Store database and invokes Search Administration database for security trimming.	Query Processing Component now under noderunner.exe and no longer retrieves properties from the property store or invokes the Search Admin database for Security Trimming when processing a query. It only fetches results from index components which simplifies things tremendously.
8	In SharePoint 2010 Search, each crawl component is mapped to crawl database which is 1:1 relationship.	The relationship between crawl component and crawl database is doesn’t exist in SharePoint 2013 Search. So a crawl component will automatically communicate with all crawl database if there is more than one.
9	To gain fault tolerance in SharePoint 2010 Search, two crawl components (one mirrored) would need to be provisioned per crawl database.	Since there is no unique relationship between crawl component and crawl database, SharePoint 2013 Search automatically gains fault tolerance by simply provisioning a new crawl component.
10	Installation: Different installation for SharePoint 2010 and FAST Search.	Installation: Single installation in SharePoint 2013.
11	Crawling Components: Multiple crawl components on single server but each component was associated with only one crawl database.	Crawling Components: No unique relationship maintained between crawl components and crawl database. All crawl component can talk to all crawl database.
12	Host Distribution: In SP2010, you could pick certain crawl components to crawl a particular URL.	Host Distribution: Host can be distributed across multiple crawl databases. The new distribution happens on the basis of Content DB ID rather than host URL.
13	Content Processing Customization: In SP 2010, we had pipeline extensibility. Which let you write custom code to use in the transformation of crawled content before it got added to the index.	Content Processing Customization: In SP 2013, the pipeline extensibility model has gone. But it has been replaced with new web service called out feature. It is invoked via triggers which you create and are based on the value of the different managed properties.
14	Security Information: Search Admin DB is storing the security information (ACL Information).	Security Information: Search Admin DB is NOT storing any security information (ACL Information). It is storing with index itself.
15	Built in BDC Connector: No Documentum Connector OR Term Store Connector.	Built in BDC Connector: New built-in Document Connector and Term Store Connector are available in SP 2013.
16	HTTP Site Crawling: Anonymous crawling was not supported into SP 2010 for HTTP Site.	HTTP Site Crawling: Anonymous crawling is available in SP 2013 for http sites.
17	Crawling - Continuous Crawl: This feature doesn’t exist in SP 2010 Search.	Crawling - Continuous Crawl: Continuous crawl feature is available in SP 2013 Search only for SharePoint sources. The default interval for this is 15 minute and can be changed through PowerShell commands.
18	Indexing - Remote SharePoint Source: This functionality is not available in SharePoint 2010 Search.	Indexing - Remote SharePoint Source: A new feature to index “Remote SharePoint Sources” is available in SP 2013 Search in which we can crawl a remote SharePoint Farm in different Geo locations using “oAuth Trust” which removes the issues of “Kerberos” authentication between the farms.
19	Search Sources: In SP 2010 Search, scopes can only be created by Search Service Admin.	Search Sources: In SP 2013 Search, Site and Site Collection Admin can configure the result sources for a site collection.
20	Data Source: Exchange is not a data source	Data Source: Exchange is a data source for a Result Source.
21	Query Transformation for a Result Source: Not Applicable	Query Transformation for a Result Source: Query transformation can be applied for a Result Source.
22	Indexing PDF Support: Advanced filter pack/iFilter being used in SP 2010.	Indexing PDF Support: Indexing PDF support is OOB feature of SP 2013 Search.
23	Format Handlers: Not Applicable	Format Handlers: New parsing feature in SP 2013 Search. Automatic File Format Detection: No longer relies on file extension. Deep link extraction for Word and PowerPoint formats. Visual Metadata Extraction: titles, authors and dates High performance format handlers for HTML, DOCX, PPTX, TXT, Image, XML and PDF Formats.
24	New Filters for Visio and OneNote: Not Applicable	New Filters for Visio and OneNote: Available in SP 2013 Search.
25	Schema Management: Search Service Application Admin can only create “Crawled” & “Managed” properties available to the entire farm.	Schema Management: Capability to do the limited schema management down to Site Collection Admins. Site Collection Admin can create custom crawled and managed properties that are only used in their site collection. The managed properties that can be created are limited – that means they cannot be refinable or sortable and it only supports text data type.
26	Schema Management: In SharePoint 2010 Search, you had to do one FULL crawl of all your contents to create a crawled property. You could then create a managed property and map it to the crawled property. But you had to do a second FULL of all your contents to populate it with data.	Schema Management: That is no longer required in SharePoint 2013 Search. To begin with when you create Site Column, it automatically create crawled properties out of it right then and there – no other FULL crawl required. Secondly after you create managed property and map it to your crawled property, you NO longer need to crawl the entire farm. Instead you can go into the list or library and there is an option now to Re-Index the list. Alternatively, you can go to the site level and choose to Re-Index the Site.
28	Query Spelling Corrections: Default spelling dictionaries and Query Spelling Inclusions list.	Query Spelling Corrections: Customization to Query Spelling Correction is now managed in term store – both inclusions and exclusions. In addition to that we still have a dynamic dictionary that is based on content in the index itself, or you can also still choose to go with a static dictionary.
29	Query Rules: SharePoint 2010 query is simple i.e. one query has one set of results.	Query Rules: Query rules allow you to have search requests from a user trigger multiple queries and multiple results sets.
30	Display Templates: Not Applicable	Display Templates: A display template is applied to the result based on the result type that it matches. You can define your own Custom Display Type.
31	Thumbnail Preview: Thumbnail preview was available for Office documents with preview of first page in word and 3 slides in PPT.	Thumbnail Preview: With new web app engine, you can browse through entire document in the preview. -          See all pages, animations, zoom in/out, and scroll through the entire document. -          The point of this is to allow users to find the exact item they are looking for right in search results – no more clicking a result, hitting back button and on and on until they find the one they are looking for. Previews only work with claims authentication and doesn’t work with Classic Windows Authentication.
32	Search Portability: Not Applicable	Search Portability: Search portability supports transferring the following items -          Result Sources -          Query Rules -          Result Types -          Schema -          Custom Ranking Models Transferring can happen between a tenant, site collection or site using export/import search configuration option of CSOM (Client Side Object Model).

Hope this helps and I would request to update me if you find some more in terms of technical / functional.

Have a nice day!!!!