What is the difference between Thermage and Ulthera?

It seems like there are people who get Ulthera and Thermage lifting procedures regularly.

What are the differences between Ulthera and Thermage?

I used to see a lot of Ulthera commercials.

There might be slight differences from person to person, but I'm curious which one is more effective.

I don't have much cheek fat, and my skin tends to be dry and sensitive. Which one would be more suitable for me?