Sharepoint Search "suggestion list" returns more results than the actual completed search

I'm trying to understand search results, which shows what I'd call a bug in any other software.

I'm searching a document library for a string (14644) in the search bar, and before I hit the blue magnifying glass, the drop down window shows 5 documents as suggestions; all are valid and exist, and I can click on any of them to get to them from the drop down suggestions.

When I actually click the magnifying glass, the result is a subset of the drop down "suggested" list (2 items) - so it's actually less accurate than the suggestion/drop down list.

Of course the document the user is after appears in the drop down list and not the formal search result.  I'm hoping to understand why?  I'll try to upload screenshots to demonstrate.