Generally speaking, they both mean to do something. But when mentioning some proper phrases, they are different. Such as"干活” you cannot say "做活” and "做作业" you cannot say "干作业"

“干” 可以解释成做（事），担任的意思：他干过管理者。

http://www.italki.com/question/150748 http://www.italki.com/question/44261 幹 : 從事、營求。如：「他是幹那一行的？」 幹活 做活 幹粗活 做針線活 幹家做活 都是可以的

Thanks :D I think by practicing with chinese people they will let me know if i use them right or wrong :P

we need to use them in the context. No obvious difference between these two verbs.Basically, we always translate "干" as "DO", "做" as "MAKE". 做饭 make a dinner 干活 do something