BLS is similar in concept. However, BLS is a lot more efficient for doing aggregation, requires less communication and is more secure than schnorr signatures. BLS requires no party setup time and can be easily used without any direct communication between signing parties. Only an aggregator is required to turn a group of individual signatures into a valid aggregate signature. Additionally, library support for aggregation of schnorr signatures is abysmal, where as almost every BLS library supports aggregation out of the box (so far in my search). I've already tested BLS quite a bit and it will be part of the VSC consensus system.

Here is a blog post that will describe the difference a better than I can. Both BLS and Schnorr have their tradeoffs. I'd like to eventually see both techniques implemented in HIVE in the future.

https://medium.com/cryptoadvance/bls-signatures-better-than-schnorr-5a7fe30ea716