The main difference is that CLIPS is a forward chaining rule system, while Prolog is backward chaining. This is a big difference in how rules are defined and how do you use them (in Prolog you start with a query always and you try to prove it, in CLIPS you just run it to get some rules dispatched).

However, Prolog is also a valid general purpose programming language, so you can actually implement forward chaining rule systems in them (see for example CHR[1] and Heiseneye [2]). CLIPS is not a general purpose programming language.

[1] https://www.swi-prolog.org/man/chr.html [2] https://github.com/IDLabResearch/Heiseneye