Yup. Old ones are smaller. Much smaller. Closer to the size of a normal infantry, whereas the new ones are probably twice the size.
New ones are quite poseable and really nicely detailed. Have the melee weapon options, as well as new designs; personally I love them. I have 20, more because I really enjoy building and posing them than because I think I'll ever actually field 20 of them...
Old:

(keep in mind that's on a 28mm base)
New:
Like all the old metal casts, they are very two dimensional. no real depth or detail in the pose; very static. The new ones give you a lot of freedom; simply having the arms out away from the body adds so much to the impact of the model.
I'm assuming you're looking at buying some - I would not bother with the old ones. Partly finecast is awful, and the metal ones will probably not cost much less than the new plastic ones. These days people get a bit snarky about using the old much smaller models when there are larger versions out now - makes a fair bit of difference to
LoS and assault with the smaller bases.