What the hell are you talking about? Both miners run on 12v power. It is the POWER SUPPLY that you either need 110 or 220 power for, it has nothing at all to do with the miner.
Sorry, in my limited experience, I found that the power supplies required to run the s7 would require you to run off a 205+ volt circuit, to remain efficient and safe and reliable for the load on the circuit. I have seen set ups running from 2 different outlets to supply power to run s7's off of 110v.
As you have more experience feel free to point him in the direction of efficient affordable reliable power supplies that will run off 110v supply for an s7.
For OP
Either way whichever of these you buy, you will probably find yourself upgrading to a more powerful miner sooner rather than later, or deciding that mining is not for you.
Good luck and happy hashing.