Wrong. Chain-split could be a subcategory of forks or at best you could call it one of the possible outcomes of forks. But they are not the same thing.
A chain-split happens in a decentralized cryptocurrency when they can not reach consensus meaning when anything less than the decided percentage of the network (which is usually above 90%) didn't accept the change.
This was never the case with SegWit since the majority voted for it.
This was also not the case with Bcash since someone created the copy without needing to reach any kind of consensus. Something anybody can do at any time just as I pointed out in my example.