-1
IMHO, ANY (number of) things can be compared (which includes contrast as needed, in my book). Depends on your view.
Often, you can't rank/rate/valuate something against another if they aren't "directly" comparable (in which case it's more of a contrast), but it's still a comparison, and is worth a LOT to some folks. I personally DO see the value in comparing, say, a Musicman to a Warwick, and describing the differences (as well as any likenesses they may have).
This kind of info is priceless to the folks who haven't had the chance to check them out, especially the newbies.
The trick is to stay as objective as possible (or use a lot of "IMHOs"). Just being aware that much may only be your opinion, your "right" could very well be someone else's "wrong", and that's the way things should be, is key. You can't go wrong that way.
IMHO