When George romanticizes about their dream ranch, he contrasts Lennie and his relationship with "other guys:"
Guys like us ain't got no families. They [other guys] get a little stake and they blow it. They ain't got nobody in the world that gives a hoot in hell about 'em!
We got somebody to talk to that gives a damn about us. We just don't sit in no barroom blowin' in our jack, just because we ain't got no place to go. If them other guys gets in jail, they can rot for all anybody gives a damn.
George, in particular, sets Lennie and himself apart from moral and work ethic perspectives. First, George points out that most migrant workers travel alone. They are like solitary predators (like Carlson--who shoots Candy's dog), with little moral conviction. They squander their money, have no home, and do not look for companionship.
Second, he believes that he and Lennie, although not blood relation, are a family. They stick together no matter what. This is especially evident given that Lennie's mental weakness makes him reliant on George. Other guys would steal Lennie's pay (even the Boss suspects this of George.)
Third, George and Lennie share a dream. They are saving their money for a patch of land and a ranch so they can retire from tramping. When Candy comes along and contributes another third, their dream is within reach.