There are two different types of breast implants or mammary prosthesis, saline or silicone. The outer shell of each implant is exactly the same it is composed of a silicone elastomer. What differs is what goes on the inside.
The saline implant is filled by the operating surgeon with saline at the time of the augmentation. The silicone implants come pre-packaged with silicone.
It many cases it is difficult to tell the difference between saline an silicone. In other cases, the difference is readily seen.
Overall, silicone tends to be softer. Both saline and silicone implants can ripple, but silicone implants tend to ripple less.