Re: Which showing classes?
I'm no expert at showing, but I've been competing in it on and off for a year now, and in my eyes a ridden hunter would look like this http://u5uk.com/you/hethelstud/myfiles/img001.jpg
or this http://2.bp.blogspot.com/_McRvrfqEN0Q/S9JsAD6dpXI/AAAAAAAAAK8/O7tl6GrwRSU/s1600/Rob_North+of+England+Show_2.jpg.
Now, obviously a lightweight hunter is going to be finer than a heavyweight etc. It's all how much bone they have around their leg I think. A hunter is a sturdy, well built horse that you could imagine doing a full days hunting all season. Working hunters have to jump a course of fences, ridden hunters/show hunters do not have to jump.
A riding type horse would be more like this http://www.jo-bates.co.uk/horses/images/blue_rondo_2.jpg
I've never heard of a riding type having to jump. They're a lot finer than a hunter and are expected to be more 'quality' - hunter horses get away with having plain features.
Also, hunter horses are ridden in all dark, plain tack. Riding types have coloured browbands and finer tack :)