Satire is the use of humor or irony to point out flaws in something, whether it be fashion, a person, but it is commonly used in politics.
Sarcasm is using irony to make something said hurtful.
Satire is used to point out flaws and be hurtful, Sarcasm is used just to be mean and hurtful, it isn't used to point out flaws. That would be your difference.