It depends.
At home, I can only get about 2megs on wifi, because of where I live.
I dont yet get 4g at home, but if I go about 15 minutes west, toward St Louis, I can get 4g. If the speed tests I have run are accurate, the 4g signal there gives me about 11-12 megs DL. So, that is much faster. And in testing the 4g signal, I noticed it is much faster than the wifi I get at home.
Some guys are reporting 25megs and over on 4g. So, as a rule, unless you have an amazing connection at home, I think 4g is typically going to be much faster.