Sorry I don't know the correct term.
Is there a big difference in protection between a case where the guitar just goes into an open area like this:
And one where it fits an area that is the correct shape for the guitar like this:
Seems like the first one is really only held in place by the neck and wouldn't support the guitar as well, but that style also seems to be really common so maybe it's just fine.
I honestly like the open style better. I've never had a problem with one, and it makes the guitar easier to get in/out, especially with a strap on.