They both had similar view of justification to god by faith. Luther thought that no good works were enough to reach salvation. Calvin had the idea that there was two group of people; the Elect and the non-Elect, which were chosen by God to be saved or not. Predestination was a key idea in Calvin's theology. He believed everything was already planned before even you were born. Luther believed that the state and the church should be separated. While on the other hand Calvin believed that the state and the church should not be subject to one another and vice versa.
Hope this gets you some ideas!
