more then 170 needles is considered a dress sock, because you have to use fine yarns and the knitting is very fine.
lower then 170 needles is usually a casual sock.
not really related to the style, fancy, colours...but more related to the thickness of the socks.
also the lenght is not an issue. Dress socks can be crew lenght and not over the calf (notwithstadning over the calf are more elegant).
Sport socks are usually under 120 needles.
those ones are sport socks.