SP 2010 and FAST Search: inconsistent search results between Search Center and search.asmx service
Problem: When querying a specific term ie "book reports" via a search web service at url http://server/contentlibrary/_vti_bin/search.asmx they were seeing less than 100 results but when searching via the Search Center it returned 100s of results.
Cause: results from the web site were set to use Stemming, so both plural and nonplural forms of the search were returned. But the web service was NOT using Stemming (aka lemmatizations) so only exact match was returned
Resolution: Enable stemming/lemmatization in the web service queries so that the web service queries will return both plural AND nonplural forms of the search term.