Unders are placed partially under the first layer of muscle (full unders are usually only used in reconstructive or gender surgery), they are called unders for ease more then anything
Overs are placed between your skin and the muscle.
It’s a decision your surgeon makes based on you personally
Neither give a definite fake or natural look, as they both achieve each look easily on different girls. The healing time is generally quicker with overs as its less invasive surgery, and you tend to get the look of them quicker (it’s not always the case)
They both tend to measure up the same, but unders need the muscle to relax before the full size is formed. Overs have a slightly higher risk of complications, like bottoming out and CC, but it’s only a few percent more
Hope this helps xx
