Ulthera is a ultrasound based technology designed as a competitor to Thermage the radiofrequency (also a sound wave) based system that can tighten facial skin and build collagen.   Neither company has done a "head to head" study comparing the two systems., that I've been able to find.  Both systems are designed for patients with mild to moderate facial laxity (sagging) which usually translates into being 35ish to 55ish depending on other factors like weight, amount of sun damage, genetic tendency to jowls, etc. 

As far as I can tell from the limited data available the two systems give similiar results with the one advantage of Thermage being that's it's less painful.  The recent Thermage systems control discomfort very well with a cooling function on the tip itself.  Two of my patients have tried both and both had a slight preference for Thermage.

 Hope this helps!  Dr. I