Why did crane man and min treat tree-ear diffrently

Crane-man is Tree-ear's guardian. He is also lame, which places a lot of responsibility on Tree-ear to try and provide for them both. The two have a kind of unconditional love. Min, on the other hand, is Tree-ear's mentor. Min is a teacher.... and employer, and a very tough taskmaster. He expects Tree-ear's best at all times, and the two begin a mutual relationship built on trust.