We might compare the two processes to two different methods of repairing a leaky roof on a house.
One is to slap some tar paper over the leaky area, and the problem is solved. Sort of.

Another way is to go to the heart of the matter, and start by reinforcing any underlying beams and struts that may have begun to rot from the water; then replace weakened boards or plywood under the worn shingles; and finally, replace the worn shingles themselves.

Which of the two repair jobs would you prefer?

HGH works along the lines of the second method. It works on the fundamentals within to effect the desired changes without. For one thing, it extends the number of times a skin cell in the dermal layer may divide.

As these cells get older, they do not function as well as they did formerly. HGH, along with other growth factors, has shown itself to be effective in restoring these cells to a more youthful efficiency in carrying out their normal maintenance work.

HGH promotes the restoration of our physiology to what it had been years earlier. It stimulates an increase in the body's production of protein needed in the formation of collagen and elastin, two of the main substances that make up the skin. As it does in the rest of the body, HGH also promotes increased muscle growth in the face, which, along with the renewed collagen and elastin, rebuilds and reconfigures the substructure under the skin. Like the injections of fat, this renewed substructure presses the skin out, but unlike the fat injections, this is renewed muscle and skin, not fat off the buttocks that will be reabsorbed by the body in time.

As HGH stimulates the body to generate more of these basic building materials, it begins to fill in the facial fissures, to take up the slack in the sagging skin by renewing it as well. It rebuilds from within, pressing out against the skin, and at the same time the renewed skin is drawn more taut over this new substructure.
In a word, it makes the skin smoother.