Hi there Oleksandr!
To answer your question, both Event Search endpoints are interacting with Eventbrite's backend search service (if you're curious, we use SOLR internally:
http://lucene.apache.org/solr/) to return an answer to your query.
In this case, the API is just the interface for interacting with our backend search service, and while we're working really hard to invest in improvements to our internal search -- it's a very difficult problem to solve.
I wish I had more insight into our search technology, but since it's not API specific, my expertise is a bit limited. However, if more information will help -- feel free to email me (
mi...@eventbrite.com) outside of the API forums.
Cheers!