Chickens can have a few different kinds of combs, pea being one of them. If your bird has a pea comb, it would not be a pure Orpington, because they have single combs. A pea comb that is triple rowed almost always indicates cockerel. Your other appears to have a single comb and looks to be a pullet.
At 16 weeks they both look like pullets, although the pictures aren't the greatest. A comb shot and side shot of the birds in a natural stance with good light would be better! Orpingtons should have a single comb so the curious one facing the camera is of mixed heritage. Three rows of peas do not necessarily mean it is a male, especially in a 16 week old bird. Here is a pic of my 4 month old easter egger leghorn cross. She developed 3 rows of peas on her comb by 12 weeks and laid her first egg at 19 weeks.