Facebook Nearby Friends vs. Tinder Geoshard Protocol

Hi, I have recently started working on a new project and have been told to look into location based matching protocols. I found that the method that FB uses to break users into similar groups seemed a bit similar to Tinder's Geoshard protocol, except for the fact that geoshard broke user groups by location, while nearby friends broke them by mutual friendships. Can anyone familiar with this please tell me if this is the only nuance, or is there something else? Or am I completely misunderstanding a part of how it works>