The color of the inner thigh is the more reliable characteristic to separate pickerel frogs from leopard frogs while the white spot on the tympanum separates the two leopard frogs. Most photographs do not show these important areas. Use your field guide to learn which body parts need to be focused upon. The color in the photograph must be true. Many larval salamanders and tadpoles are, unfortunately, almost impossible to accurately identify using only a photograph.
Measurements also help.
Turtle measurements include only the shell and not the body. Remove the turtle and measure the distance between the lines. A third measurement is the shell height, which can be important in identifying box turtles. In general, the markings on the belly and back of New York's snakes are fairly distinctive. Venomous snakes have vertical pupils and a pit on either side of the face.