It IS tricky - having tried both I find riders from each discipline have little understanding of what the other entails. Common from English is that some believe western horses have NO impulsion, and from some western on English riders that they 'pull on their horses mouths'! Neither being correct of course - western horses are still looking to engage quarters and English horses are ridden into a contact...

I've even heard one western person say they would never consider riding a thoroughbred because they are ALL so scatty - she was a tad surprised to find my extremely well behaved paint is a tax! Ha!