beginner= just started riding, learning
advanced beginner= can ride walk, trot, canter on a good horse and has basic knowledge of grooming and tacking up a horse.
beginner intermediate: Has a more solid seat, walk, trot, canter. Knows more about horse care, tacking up, and riding. Can do jumping and can ride a more difficult horse. The should also have good ground skills.
Intermediate: Starting to ride with an independent seat, learning about contact, impulsion and balance. Learning how to get the horse on the bit. Can jump higher now and handle hot horses on the ground and in the saddle.
advanced intermediate: Riding the horse on the bit that is already trained, can jump higher(if they jump). Can handle a hot horse, learning to ride with their seat more. They can get a horse better on the bit. They can start learning about training horses and can be properly riding green horses and more advanced horses.
Advanced/experienced: Have been on many different horses, have excellent skills on the ground and in the saddle. Can ride much more difficult horses and do more advanced movements in dressage or jump higher. Have a sense of balance, impulsion, and are collecting horses. They also have knowledge of nutrition, first aid, training, lunging, use or training aids properly.
Expert: can handle any horse, train horses.