I don't have a 70D, but I do still have my 5D II. The two camera really are completely different.
There's the obvious distinction that one is full-frame and the other is crop-frame. Sure the photo-sites on the 5D II are larger so they are more efficient at gather light and that translates to lower noise. And sure the crop-factor difference means that a 24-105 lens on a 5D II body will really achieve quite a different "look" than the same lens on an APS-C body.
But beyond that...
The 5D II has a focus system a lot more similar to the older Rebel bodies. It's a 9 point AF system with 8 single-axis focus points configured in a roughly "diamond" shape pattern and a single "cross-type" AF point in the center.
The 70D has a 19 point AF system where all the points are cross-type (it basically pinches the 7D's focus system with the exception that a 7D can do spot AF and the 70D cannot.)
The 70D also has a fairly quick continuous burst speed at 7 frames per second. The 5D II is 3.9 (slightly better than half as fast.)
If your'e doing landscapes, portraiture, and lots of low light... the 5D II is for you.
If you're doing wildlife, sports, and action photography... the 70D is probably for you.
Both do video but the 70D has the continuous focus tracking during video -- and 5D II does not.