There is a distinct difference between shoe insoles and orthotics.
A shoe insole is typically a thin, 1/8th inch or less thick, foam or polymer gel material or a combination of both. It provides cushioning for the heel and the ball of the foot.
An orthotic differs in that it typically adjusts how the foot functions and will provide support to the arch area. Orthotics are more functional concerning arch or heel pain.
Some orthotics are full length or can be a 3/4 length. A full-length device will provide arch support along with a cushioning material under the ball of the foot and toes. However, the 3/4 length can be easier to fit in some shoes with limited toe box space.