Breeches are worn for comfort mostly for English riders. They can be knee patch or full seat, made from cotton or speciality fibres that repel water and coffee!
Full seat breeches are often worn by dressage riders who like to feel a more secure seat. Knee patch or Euro seat are worn by Hunter/Jumper riders who like to feel a little less restricted in the saddle.
There are thousands of brand names available on the market today that fit all disciplines and budgets.