The little indent in the pistil-less pre-flower.
The one that opened was the first, the preflower. In this case the bananas are bursting open en about to drop pollen. As long as there are not bananas dangling you don't have to worry either.
I'm not sure the other is female, picture is too vague. Males aren't always entirely symmetrical when it comes to preflowers and stipules but looks like a female calyx in the first thumb. You can check with a loop if you really want to know now. If female, it will have 2 tiny white/clear pistils (hairy thingies...) coming out of little pear shaped balls, like this one:
