Both float and absorb berthing energy — the difference is what's inside, and it decides maintenance, damage tolerance and where each fits best.
Same job, different core
A pneumatic (Yokohama-type) fender absorbs energy by compressing the air sealed inside it, giving high energy absorption at low reaction force. A foam-filled fender does much the same job but with a closed-cell foam core inside a reinforced skin — so it holds no pressure and cannot be punctured flat.
Choosing between them
Pneumatic fenders suit ship-to-ship transfer and large-vessel berthing where their energy characteristics are ideal and they can be maintained. Foam-filled fenders win where damage tolerance and low maintenance matter most — permanent, exposed berths and unmanned installations — because a cut skin still floats and keeps working.