Are usual raw BTC and BCH transactions differ? Can I make BCH transaction with bx? Is it possible to create raw BCH transaction with bx tool, just like I do it with usual bitcoin transactions?

If they are, I suppose it only takes to broadcast it in BCH network?
Yes, they are different, because of replay protection.  BCH computes the transaction digest for signing in a different way.  A transaction signed with this method will appear to a BTC node to have an invalid signature, and vice versa.

The bx tool does not appear to have been updated to support this modification, so you currently won't be able to use it to validly sign BCH transactions.