Neutrality. Scales better. The treble is in-offensive. No upper mid peaks. Cheaper.
I wouldn't say the HD700 is worse or better than the K712, just not worth the MSRP by far. And definitely not for young sensitive ears.
You should look into modding the K712, they open quite nicely, and the vocals are some of the most accurate I've heard for the price range.
I have to agree personally. I found that with the HD 700, the treble was too much for me to bear given I have young sensitive ears, the HD 800 I heard bothered me even more in the treble than the HD 700 as I found it even brighter.