Iran's position has a couple strategic advantages over Iraq's position.
On the pure military side:
On the ground alone, Iran is relatively easily defendable, as long as a number of tentative Allies (Turkmenistan, Azerbaijan) don't "defect" and are used as staging grounds. Iran also has the manpower to actually build the necessary envelope for such a ground defence.
In the air - well, that's been well over-discussed by now. To make it simple: Iran's favoured slightly by terrain if it can exploit it; and it's hindered by technological/supply problems (both flying and ground material). Iraq pretty much didn't have a credible airforce anymore by '91 btw, since they simply handed its remains over to Iran.
On the sea, shaky at the moment, considering Iran's experience with both symmetric and asymmetric naval warfare, and wide use of shore defence systems of various kinds. At least the former Iraq was seriously lacking in '91.
On the counter-strategy side:
Iran definitely has advantages there compared to Iraq '90. Namely of course the destabilized war zones on both sides (Iran, Afghanistan), with two other tentative ones (Pakistan, Kurdistan). Playing it right, they could create definitive problems there.
Unlike Iraq, there are possibilities for Iran to exploit to avoid some supply problems, in case of a more drawn out sitation; in particular via Azerbaijan and Turkmenistan. In addition, Kazakhstan and Russia itself would still have possibilities via the Casbian Sea. Unlike that situation, Iraq was pretty much cut off from all sides in '91, except for Jordan's neutrality.