What's the difference between ulthera (HIFU) and ultherapy?

HIFU means High Intensity focused Ultrasound, and Ultherapy is one device/treatment that uses HIFU. The effect of HIFU depends on the depth at which the ultrasound is focused. Ultherapy places it fairly shallow, so it stimulates the dermis of the skin. Ulthera is the company that developed it.

Ulthera used to be the company that originally sold the Ultherapy device.  The device is now owned by Merz Pharmaceuticals, which also manufactures Radiesse and Belotero.  HIFU refers to high intensity, microFocused ultrasound which is the type of energy the device uses to create the lift and skin tightening it's known for.  

Thank you for your question.  Ulthera is the name of the company (Now owned by Merz Aesthetics) and Ultherapy is the name of the actual treatment.  They are used interchangeably and are essentially the same thing.  Regards, Dr. Matt Elias