(I apologize for the super late response, just now I found out about this post)

I'm the author of this, and here's the difference: Neutrino is a privacy preserving alternative to a third-party address indexer. It's a way to sync your wallet without requiring a centralized third party like an electrum server. However, neutrino doesn't validate blocks and transactions, it doesn't even authenticate the filters it uses.

Floresta is a fully validating, lightweight Bitcoin node. It's like running Bitcoin Core, but using way less resources due to an aggressive pruning and Utreexo.