I have both the regular fleece-lined Mammoth clog and the Woolly Mammoth. The difference in fit (with the same sizes) is very noticeable. While my foot has plenty of room (even a bit too much) in the regular Mammoth, it fits snuggly into the Woolly Mammoth. It is quite tight with regular socks, although I even followed the recommendation to order a size up. Wearing thicker winter socks, I am unable to fit my feet into these. One star deduction for that because I feel that with having ordered one size up, I should be able to wear thicker socks AND fit into the shoes.

That said, here is what I like about the Woolly Mammoths: I love the adjustable heel strap. As a matter of fact these were the reason I bought these clogs in the first place. It makes for much better and stable walking. Also helpful in colder weather: the fewer holes on top of the shoe as well as a much better-profiled sole. I imagine this shoe to get better traction when it is slippery outside.

Just wish these came in more color selections! I bought the black with the gray lining but feel it is a bit drab...(but hated the other colors even more so finally settled for this combo).

The only other comment I have is that I am not sure the heel strap and the somewhat different sole warrant a $20 higher price. But all in all I am happy and am sure I will be wearing these a lot this coming winter.