The Watch 4 Classic is a little bulkier and it has a rotating bezel on the top of its face. It is also made from stainless steel. The Watch 4 meanwhile, has a tapered black bezel on the top and it is made from aluminum.
There is a speaker on the Galaxy Watch 4 Classic, so you can take calls on the watch itself. Callers did not have issues when I received their calls on the watch, and the speaker volume was adequate when I raised it to my face.