In 14.1 , it matches with the word which
starts with the characters you typed in select dropdown field
In 17.1 , it matches with the word which
contains the characters you typed in select dropdown field .
For example , see the following screenshots:
When we type s, it is showing all records which contains 's' :
<Please see attached file for image>

When we type sa, it is showing all records which contains 'sa'
<Please see attached file for image>