Frankly it's silly to argue over the different "types". It's like arguing over Apples and Oranges......or if you don't like oranges, then Grapes and Pears!!!
Our "B" Minis and Miniature Shetlands happen to look a bit like the Arab "type", but with some substance. The modern Arabs have lost some of their bone, IMO. We also happen to own a full sized Arab.
Our "A" Minis are more medium boned and remind me of another full sized horse we also own, which happens to be a Morgan/Arab cross!
Here's a Test......Take your "perfect" A or B sized miniature horse......no matter WHAT SIZE and place them in a backdrop where you can't tell their height. It needs to be a side shot. Then, look at the length of leg, the slope of the shoulder, the hip, tail set........how the neck comes out of the chest........the triangle and shape of the face/head. If everything looks balanced and it's as if the horse is FULL SIZED......That horse has PASSED.