First of all, the female grass turtles have flat ventral armor, while the male turtles have obvious pits.

Second, the female's tail is shorter and thicker, and the cloacal hole is within the back edge of the dorsal armor.

Third, the male grass turtles have black limbs, head and neck, and carapace. The females are brown with a green or olive green pattern on the head and neck.

The two turtles are similar in size, so it's not a problem to keep them together.

Grass turtles can be fed turtle food, fish, meat, shrimp, snails, and breadworms.

Note: The upper part of the turtle's ventral armor in the first photo, close to the neck doesn't seem to be very good, be careful not to rot armor disease.