Drew's Dad is right. The difference between CI and HA is that Cochlear Implants DOES NOT amplify and Analog/Digital Hearing Aids DOES amplify.
Cochlear Implant bypass the need of Outer/Middle Ear system. Cochlear Implants deliver sound directly to auditory nerves connected to cochlea, also bypassing the damaged cilia inside the cochlea.
Hearing Aid send amplified sounds thru earmold into outer ear which make eardrum move wildly than normal causing the middle ear system to pump bigger than normal to oval window causing those damaged cilia to move somewhat.. thus making deaf hear some sound that are pretty outside the speech banana range. Those who wear HA are putting more stress on eardrum eh.. 
When I had HA, I only could hear in 50DBL range now with CI I hear in 20-30 range which is inside the speech banana.