Lennie could not survive by himself. George looks after him. So George struggle for survivor is twice as hard as it is for most men
As migrant workers, they drift between towns looking for work so they can support themselves. This is made difficult by Lennie getting them into trouble, which cause them to leave employment opportunities.
Man vs. man is apparent when Lennie is pitted against Curley and his wife. Man vs. society is a conflict present with the character of Crooks and the racism of 1930s America, while man vs. nature is evident with Candy fighting his age and deformity.