Grooming wise what is the difference in friesian horses and other horses?

Grooming can be very different for different breeds but more on the time factor. Example: I had a cob with a long thick mane and tail, plus a ton of feathers. Feathers need daily grooming and sometimes trimming so they don't drag on the floor. You also have to use tooth comb to get out all the dead skin on insanely thick feathers. Feathers can also be a problem when it comes to mites so often need treating. You'll likely need something to help detangle hair and expect to spend more hours doing it.

They don't need more bathing necessarily but, as with any black horse, you'll want to finish with a dry or damp cloth and wipe it over their coat to remove dust and skin that can show up. This should be done with every horse after grooming.

In general, the entire washing and grooming ritual is the same for all horses. It varies perhaps more with the style and kind of work your horse is doing. For shows you might want to put hours and hours into fussing the the mane, tail, forelock and feathers, being careful, though, not to overdo the washing and cause irritation.

For workhorses you would focus far more on the comfort of the horse. You may have noticed that a properly groomed horse will delight, after the show or competition is over, in going out and rolling in dust and mud.

There are special tricks for helping a horse preserve a long and flowing mane and tail. Similarly for hoof feathers, I would bet.