What is the difference between MicroDermabrasion and HydroDermabrasion?

What is the difference between MicroDermabrasion and HydroDermabrasion?
MicroDermabrasion is performed on dry skin and uses a diamond pumice tip to provide maximum-strength physical exfoliation by sanding the outermost skin layer. It’s best performed on heavy dead skin, rough thick skin, severely pitted skin or deeply pigmented skin. A Dry MicroDermabrasion may scratch the epidermis and may cause temporary redness or an uncomfortable sunburn burn sensation afterward. HydroDermabrasion uses a diamond tip as well, but also uses saline water or other serums as an exfoliating and cleansing medium. It is gentler than MicroDermabrasion and is more suitable for those with sensitive skin conditions. Throughout the process, each hydro-tip glides along the skin without friction and irritation as it exfoliates dead skin cells, painlessly extracts blackheads, and infuses skin with vital nutrition and moisture. Unlike a MicroDermabrasion, HydroDermabrasion does not produce heat or inflame the skin, so HydroDermabrasion can be used safely and painlessly to treat acne sufferers and to exfoliate rosacea and to correct other sensitive skin conditions.