What about the length of this jacket? is it a big difference between the L and the XL?
Probably 1 1/2 inches. For your reference, the model above is 6 feet tall and he's wearing a large.
1 inch is the difference. I am 6'1" and skinny and i wear the large. It fits perfect. My room mate actually has the same jacket (twinzies) and he is about 5'8" and skinny and he wears the med. He is skinny as well. Hope that helps.