This is a good point. It's difficult to tell simply by looking at polls that one is more accurate than the other. You have to look below the hood . . . check the engine, kick the tires. And if you find something that raises a red flag, then you may be on to something.
Because ultimately the poll numbers depend on (1) questions asked, (2) how hard undecideds are pushed, and (3) the cross tabs, any one of these can affect one company's projections for a particular part of a state versus another.
I guess, as you say, we'll find out on 4/22.