The difference is obvious, boy! Many people have previously commented that Libra will greatly affect Bitcoin, this is a wrong thought! Libra is a fixed currency used for payment on facebook platform, related partners. Bitcoin is widely used in many fields, being the leading exchange currency used by investors.
Actually, Facebook coin scope expands across the whole financial system, and that is why till date, it has been threatening government, if it was just designed as payment for their Facebook platform alone, I am sure that all these issues surrounding it from government and from individual would not have existed, but even with their wide scope of services, it will still be very much impossible for Facebook to have any negative effect over bitcoin.
One of the disadvantage of the coin is that it is a decentralized coin which is far from the objective of cryptocurrency and will make bitcoin remain the only significant coin that is truly a decentralized coin people wishes for, so If I may tell you, I am not scared of Facebook coin release, it will help me and will still not affect my use of bitcoin or affect my investment because the present community would never leave bitcoin for Facebook coin.