Yes, the 7950 has a 384 bit bus and consequently a higher memory bandwidth, it has more shaders, rops, texture units.
It's a much better card : http://tpucdn.com/reviews/AMD/Catalyst_12.11_Performanc...
For 1080p, the 7950 is a good choice, and it comes with crysis 3, the 7870 comes with tomb raider, bioshock comes with both.
Yes, the 7950 is faster than a 7870, but it is only one level higher on Tom's heirarchy chard. That is not so much difference that you would notice it outside of a synthetic benchmark.
If you have the funds go ahead and buy the 7950, otherwise you will always wonder if you should have.
It is the same rationale for those picking a GTX680 vs. a GTX670.
Using the data from the graph linked by Django (and based off the Newegg prices on the Gigabyte 7870 and 7950), I figured out the price/performance values.
The 7870 has $3.05 per 1% of performance, while the 7950 has $3.30. Not as great value, but that's is to be expected as you get higher up the performance ladder.
So if you get the 7950, it will be worth the extra cost.
And Crysis 3 is looking to be better than Tomb Raider, thats another reason why.