Contrast means to show the differences ie compare or appraise in respect to differences . Contrary means to show the opposite meaning or action On the other hand means different facts or views of the same situation or thing. Long time no see. How have you been?

in contrast = 哪像 on the contrary = 反而 on the other hand = 另一方面 The clue to the differences are in the words "contrast", "contrary", and "hand". Here is another useful resource: http://www.mdbg.net/chindict/chindict.php