The Major is able to pilot Clarice remotely over the net, much like she does with Chroma. Clarice's prosthetic body is not nearly as durable as the Major's standard body, and lacks skin protection, rendering it much more vulnerable to physical damage.
Clarice is however much lighter due to it's lack of armor and is still highly-functioning, likely able to move faster and jump higher than the Major's normal prosthetic.
The body did sustain large ammounts of damage to it's internal systems when used in a highly physical combat situation. Clarice eventually required high-level maintainence.