Hi, Eva. In answer to your question, I don't know of any such tool offhand, but a quick Google of "compare Word and Framemaker functions" turned up a page containing links to various comparison documents. The versions were old (Frame 5.5) but most of the significant functions were established in Frame by then.
You might find that someone has already done a bit of documenting the vocabulary differences between similar functions. It's the problem of the Web -- yes, all the information in the world is on it -- no, it's not easy to locate specific content such as what you need! Good luck. --Nancy