Ultrasonic shot peening is a production process in which kinetic energy is transferred to the peening media via ultrasonic waves, unlike conventional shot peening where either compressed air of rotating wheels are used to propel shot against a target.

Ultrasonic shot peening is performed with an enclosure and claims several improvements over conventional shot peening processes. There are several articles available that describe the technology and its application.

https://www.shotpeener.com/library/pdf/2016018.pdf

SFFB propels small particles (a few 10's of microns) at very high velocities 300-100m/s at a substrate - often using cold spray equipment. The process is capable of producing a nanocrystelline surface layer on the substrate.

Again, there are many available references including this one

Article Nanocrystalline Surface Layer on AISI 52100 Steel Induced by...