Obviously there is the functional differences between males and females. The male provides the sperm and the female provides the eggs and when combined they eggs are fertilized and, hopefully, grow into tadpoles. The female American Bullfrog is said to produce up to 20,000 eggs. Females bullfrogs are typically larger than males. Males have a external ear drum called a tympanum that is about twice the diameter of the eye. Female tympanum diameter is about the same size as that of the eye.
Female frogs are usually larger than males, this being so they will be able to support the weight of the male during amplexus. There are exceptions to this rule, like the male African bullfrog who can be twice as large as the female. The male has a yellow throat and gives a loud "jug o rum" call during the mating season, while the female's throat is white
http://www.livingunderworld.org/caudata/database/salamandridae/cynops/
no nodifference
touch
males have longer tails
If a girls belly is lower its a girl . and if a girls belly is higher then its a boy. that's how you can tell if its a boy or girl just by looking at her belly.
you can tell from the in larged stomach or belly
Ultrasound. You can not tell just by looking at your belly.
See, "Can you tell the difference between a girl Rough-skinned newt and a boy Rough-skinned newt".
When taking care of a pet it is important to know how to tell if they are sick or not. A Fire Bellied Newt would be lethargic, and show no interest in food or water if it was sick.
Look on the tummy. If you see a "belly button", then it is a boy. (Hint: it's not really a belly button) If not, then it's a girl.
thar r two ways u can tell from a girl and a boy newt number1males have longer tails than females number2 males have to bumps by ther tails and females only one bump by ther tail well i hope i helpt :)
i boy will have a big belly and the girl will be aggressive.
when she looks like she has a baby in her belly.
That is a very good answer reader, well it actually depends of what kind of frog is is like if it is a bull frog you can tell but if it is a fire belly frog no one knows.