Depends on the brand really...but for the most part it should be similar.
I have Bauer Supreme One75s (2010) and used the current Bauer Supreme shell for it...they said to use the same size so I got a small for both and it fit great. I thought it would be too tight but it fit right over the pants like a glove and gave me the same amount of mobility. Didn't feel any heavier either. Might have a bit more hotter since the vent holes didn't quite match.
They're maybe a half inch longer than the pants, but it still fit around the middle of my knee cap. I think they're all a bit longer to cover up any color you're hiding under the pants.