App Store: Are app names more important or app display names when it comes to searchability?
The app display name is taken into consideration when apps are being searched.  However, that's only 1 thing Apple considers when determining what apps and what order apps are returned during a search.  They can also use app review score, how long the apps been in the store, reputation, etc.  

In short, nobody outside of App Store staff knows exactly the formula used to determine how search results are displayed.  Right now everyone is just guessing what they think will be returned.  The best thing to do is name your app properly and use the right keywords.  This link will help guide you in doing that: https://developer.apple.com/app-store/search/

Apple just announced they will be limiting app names to 50 characters (not 50 letters so spaces and special characters count).