The Niqjab, which is the full-face hijab is much more prevalent in Saudi, than in Iran. In fact, in Saudi, if it's not the niqjab, then it's definitely the burka. Most young women in Tehran wear the hijab, not the burka and not the Niqjab.
While Sharia Law is the law of the land in both countries, women actually have more rights in Iran, than they do in Saudi. Women in Saudi literally cannot go outside without permission from their men. Women in Iran can drive, they can vote. Tehran, despite years of theocratic dominance, is MUCH closer to Istanbul, than Riyadh is.
The difference between both countries as it relates to the west, is the official policy posture of their respective governments as it relates to the US and to Israel. But, strangely enough, culturally Iran is much more western than Saudi.