I wouldn't exactly say I'm in the know, as such... I never played the original Elite (the tape always failed to load, right at the sodding end!) or the spin-offs.
I've had a bash at the first Alpha release and found it very solidly focussed on the gameplay/spaceflight aspect. That's about it. I won't be buying it until it's ready, as I want to be blown away.
SC is about giving you everything in the universe it possibly can, whereas Elite is focussed on doing what the original did and just delivering the absolute best gameplay in creation.
AFAIK, you will be able to land on planets. But for the most part, it will be a very solid spaceflight-centric game. It will take months top get anywhere near even Dangerous, never mind actually being Elite.
There is an online multiplayer aspect too, though again I purposely haven't been reading too much about that myself.
I'm sure a five-minute Google will be your friend, though
Either way, I'm already paid up on SC and, on the strength of what I've seen so far, I most certainly WILL be buying Elite: Dangerous!!