Elanguest, I had looked up not only one dictionary before posting here:) You're right - I get the same definitions. I've put this question on this forum, because, in some multiple choice tests one has to choose any of these two words for a sentence and I don't see any big difference. Now I don't remember which test it was but whenever I come it across again, I'll put it here. Anyway, thank you
Just think about it: if there are so many things that it's impossible to count them, then they are innumerable. If there are many but it is theoretically possible to count them, then you can't say they are innumerable; you should use the word numerous.
Now, I got the point! The issue is that in my native language, even if they're countable and are too many, still you can use "innumerable". Thus, "innumerable" and "numerous" are complete synonyms. Thank you very much Elanguest!