Ultherapy and dermal fillers are completely different.  Fillers may help slow down the loss of collagen, but Ultherapy can replace collagen already lost.  Ultherapy tightens and lifts skin to stimulate the production of new collagen in the skin.  The collagen producing benefits from Ultherapy can actually make the skin stronger and more toned to restore the skin to a more youthful condition.  Ultherapy can make the skin stronger and thicker but cannot replace lost volume as fillers can.  An Ultherapy treatment may reduce the amount of filler needed, however, so the two in combination complement each other beautifully.