What connection are the both using? What router are you using? How is your network set up? There's a whole slew of things that could be doing this. I just got 23.75 Mbps down on my MBP and 15.33 Mbps down on my iPad 4, both connected to a 5 GHz 802.11N network. Ironically, my upload speed from the iPad was actually 2 MBps faster than my MBP... interesting.