Well so what are the difference between two of the app ? well the difference between Find my Facebook Friends and Apple's app is that,the people you share your location with are from Facebook. Both you and your friend need to have Find My Facebook Friends installed in order for it to work.
If you are worried about the privacy, then you must know that Find my Facebook friends gives you a extra options when it comes to sharing your location that means you can actually control your location sharing. You can choose to only share with certain groups you have set up on Facebook or with specific friends.You can also take the opposite approach and choose to share with everyone except the groups and people that you specify. You can similarly set up Find My Facebook Friends to notify you when someone is nearby.
Another difference between Find My Facebook Friends and Apple’s Find My Friends is that in this new Facebook version, you can actually watch your friend travel on the map – you have to refresh Apple’s app to see an updated location. While
Download Find My Facebook Friends App: