Poster Zarnav hit it right on the money with his answer.
Where most people could get the out of pocket max is getting care with an out of network provider. All insurance companies have "negotiated" rates they will pay for services, which they will call "in network". But if out of network, you then become stuck paying more, since the insurance wont.
Another consideration is to see if the doctors you see are on both plans. Many times, a person will choose one over the other since if their doctor is not on one, they will then be forced to find another doctor.