Cheers Ameerat. In this context, we could mean either of two different things by "equivalent".

(a) "Equivalent" in the sense of both being the original source of the image containing all the possible information; the base from which we do any further work.

(b) Equivalent insofar as they act in similar ways and have similar capabilities.

If we mean sense (a), then yes, the negative and the raw file are indeed fairly exact equivalents.

If we mean (b), then they are not. A raw file has capabilities that no negative (or slide) has. In particular, you can change the white balance very effectively and easily. To change the white balance of a negative, you have to go back and re-shoot using different film or different filters or even different lighting. (You can probably do stuff in the developing stage too, but I'm no dark room wizard and I'm only guessing that bit.) Once it's developed though, white balance (and some other things) are set in stone, and while you can still make adjustments to a print (using light, exposure, filters, type of paper and doubtless a few other things) you will always have to work from that set base. In this sense, the negative (or slide) is much more like a JPG or TIFF: you can adjust it, but within the limitation that you can only take away things that are already there, you can no longer add back in anything that the original negative or TIFF or slide or JPG does not contain.

I'll stand by my single word as a good, short summary, but readily agree that a longer and more subtle answer is better.