New Garter snake help

[Willhorner]

Good evening!
I've had corns and kings for years, but I just purchased what was represented as 2 juvenile garter snakes, but turned out to be adult and young adult easily. This is OK as they should have a higher survival probability but caught me a little off guard. My current question is how do i determine which is the male and which is the female? the smaller one is not very active, but the larger one is what i would describe as hyper. The large one is eating well, then smaller one not so much yet.
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[guidofatherof5]

Post up some underside tail/cloaca photos with the tails hanging straight down and we'll sex them for you.