Dry ice blasting is similar to sand blasting, plastic bead blasting, or soda blasting where a medium is accelerated in a pressurized air stream to impact a surface to be cleaned or prepared. But that's where the similarity ends.
Instead of using hard abrasive media to grind on a surface (and damage it), dry ice blasting uses soft dry ice, accelerated at supersonic speeds, and creates mini-explosions on the surface to lift the undesirable item off the underlying substrate.