When answering this question about incrementum, I recalled the similarity of the suffixes -mentum and -men. If the linked Wiktionary pages are to be trusted, they are etymologically related, both containing the PIE suffix -mn̥. But what are the differences, if any, between the two when used for derivatives in classical Latin? In particular, is there any difference in meaning when both suffixes can be used?
The lists of words ending in -mentum and those ending in -men seem to contain somewhat different kinds of words, but I can't really put my finger on the exact difference. I get the impression that -mentum is restricted to deriving from verbs while -men is not, and not all words ending in -men seem to be derivatives. Any insight into the difference of these two suffixes would be much appreciated, whether based on observations of differences in use, etymology of -tum, derivative descriptions in a Latin grammar, or something else.