pros use pillow bag gloves

[Redd Foxx]

When you use your hands for a living, hand heath is a priority and Winning are, by far, the best for hand health.
As far as protection goes, you're confused. Bag gloves put the protection up front, where you strike the bag. Sparring gloves shift some of the padding back toward the wrist, for blocking, but are generally a little less protective up-front.

However, these days, many gloves are somewhat universal in their application and just called "training gloves", with the "bag gloves" featuring velcro.

[Damn Wicked]

why do pros use pillow 20oz winning gloves on bag work?
why do every brand market bag gloves if sparring gloves offer more protection?/

They probably need to save wear and tear on their hands. Years of boxing will take a toll on your hands, so you'd better protect them to maximize performance life.