If it's white with pink eyes/leg and skin, then it's an albino and very, very rare.

Otherwise, it would be a domesticated bird, one that was either released or escaped from captivity. Unless their wings have been clipped (and the feathers have grown back yet), they will act everything like their wild counterparts.

Be careful about harvesting "white" wild turkeys...check your state regs and be sure that it's legal. In some states, that's a no-no...