Most definitely. they are unusually full, round, and hard, and usually sit unnaturally high on a woman's chest.
It all depends on a few things like what top you are wearing, how good the op was and how big they are.
If you have huge implants then people may notice that they have grown to an abnormal size in a short time.
If the surgeon has done it many times before and has good experience then you will have small faint scars.
Actually yes you can - they look very round or have a distinct outline, also you can tell by how perky or upright they stay with no bra or stay "up" when lying on their backs not naturally falling to the sides too much.
It is super easy to tell real from fake so if you go fake, don't go super duper fake!!!!
Typically, real breasts have an increasing gradient that has no sharp points. (To use a calculus sensibility, imagine a y = -cos(x) that is differentiable at all points between 0 and pi. If there is a point where the curve is non-differentiable, you have fake breasts.)