Questions about slot and slotless motors

I would like to ask a question about brushless motors.
Anyone could answer me the followings?

What is the difference between a slot and slotless brushless motor?
What are the pros and cons between them?
Among the brushless motors in the market, which brand is a slot motor and which brand is a slotless motor?
As I know, a slot brushless motor runs cooler than a slotless motor inherently. Is that right?

Thank you.