The 4710 and 4720 are just minor speed refreshes of the same 4700 CPU. Shouldn't be any cost difference for the newer refresh (perhaps a discount for the "older" refresh). In this case the Intel wireless may be worse, its a 1:1 wireless unit...even a lesser brand 2:2 is probably going to have a better more stable connection. Though it does also depend on the design/routing of the antenna as well.
If you've played with the Lenovo in person and think it has better build quality, then that is probably exactly where the extra cost goes...into building a stronger laptop.
I cant vouch for one or the other. If the specs are similar my objective was to add build quality to your decision...which looks like you have already investigated.
Something else to consider if you have more time, that is the possibility of newer CPUs from the Broadwell family (i7-5700 MQ?).