The term casket can be used to mean a coffin. The terms are interchanged commonly. So an English speaker would know what you meant if you talked about the casket at a funeral. Note that the word casket has other meanings so context may be important. I had never heard the term Catafalque before. But having found it in a dictionary, it is not a coffin. It is the decorated platform that a coffin is placed on. Only used for distinguished persons and apparently it is mobile.

Catafalque= A decorated wooden framework supporting the coffin /casket of a distinguished person during a funeral or while lying in state.