The difference is that Steam offers a lot of useful functionality now...
No, it's exactly the same thing. I could just as well argue that GFE offers a lot of useful functionality, and for many people it does.
...and it's way better than your typical DRM.
Only if you want it's features. Otherwise it's one of the most invasive forms of DRM conceivable. You have to sign up to a service with your email, install 500MB of client, run it and it's 3 processes in 100MB of RAM every time you launch the game (or have it start with windows), close it manually afterwards (even origin has the decency to provide a close-with-game setting), have it download 100MB updates on a regular basis, be screwed around with verification emails every time you install it on a different system (or reformat the same one), etc. Just imagine if securom or something did all that. If you find steam's other features valuable, then this is a fair tradeoff. But if you don't, then Steam is nothing but an extremely bloated piece of DRM. It, just like GFE, should be optional.
No, it is nothing like Steam. It is a program required to install drivers for their hardware and requires an email.
How do you sign into Steam?
Drivers to make your hardware run... and heaven forbid I want to run older drivers for a specific game.
Yeah, just like heaven forbid I should want to run an older version of one of my Steamworks games because the latest patch has broken it on my PC. Steam forces you to install the latest version, because Valve knows best.
Although I am loath to agree with Tential, he's right in this one instance. Steam is a perfect analogy for what is happening here. If the morons at Nvidia go ahead with this ridiculous plan, then it won't be long before everyone just bends over, falling again for the "friendly DRM" trojan horse.