In the US, the Holland Lop is at the max a 4 lb rabbit that sits upright, lightly on it's front feet. They are a true dwarf. When set up properly they should look like a n with a head on it.
Mini Lops on the other hand are set up completely differently, more like other commercial and compact breed. They are set up with their front feet resting below their chin, and their hind legs even with their hips. Ideally, they should look like half a basketball. They are also to be between 4.08 lbs and 6.08 lbs.
You are right, their ears are different lengths too. Holland Lops are allowed to have their ears hanging up to a 1 inch below the jaw line, where as Mini Lops do not have length requirements, but their ears should balance with their head.
This is what I was taught in 4H, Holland Lop ears go right below their jaw, Mini Lop ears lightly touch the table, French Lop ears fold over on the table, and English Lops have SUPER long ears. They have to be a min of 21 inches from tip to tip.
Hope this helps.