Here's a detailed article on this topic by CNBC:
cnbc .com/2019/06/18/the-difference-between-bitcoin-and-facebooks-libra.html
In my view, the biggest difference between Facebook's Libra and the Bitcoin is that while Libra is a Stablecoin, Bitcoin is not!
Very welcome to Libra into crypto world. Though it has some problems initially by USA government but i think for time being it will be more effective coin to all. I think its an another turning point of Facebook and CEO.