First, Iran is Shia, not Sunni. So, no, they are not Wahabi. Just like the Queen of England is not Catholic but rather Anglican (Protestant).
Second, it is arguable whether Iran is more liberal than Saudi Arabia. In some instances it is. In others it is not. This is a matter of religious debate. Just like Saudi Arabia, as a Muslim, you can not simply stop being a Muslim or convert to another religion or become an atheist.
Iran also has consistently persecuted non-Shia Muslims (including Sunnis, Sufis, Ahmadiys, etc.) as well as the Bahais who are the largest religious minority in Iran.
The reality is that Iran implements Sharia just like Saudi Arabia. They chop off hands, blind people, hang people in public hangings off cranes, etc. The Iranian version of Sharia is a little different than that of Saudi Arabia. This is because they are Shia and have a different version of Islam, not because they are full of sugar and spice and everything nice.
Third, Iran certainly does exports their version of Islam just like Saudi Arabia. The most obvious one right now is Yemen where the Houthis are being used by Iran as a proxy to fight Saudi Arabia.
But Iran has also funded Shia Muslims in Nigeria [1] and elsewhere in Africa. They also created and continue to fund Hizbollah to the tune of hundreds of millions of dollars a year as well as shiploads of weapons and explosives which Hizbollah uses as a terrorist organization to perpetrate untold atrocities.
Iran has also perpetrated many acts of aggression and terrorism globally: Kenya, Thailand, Argentina (AMIA bombing), Paraguay, etc. [2]
[1] http://www.thedailybeast.com/articles/2015/12/23/nigeria-s-k... [2] http://www.telegraph.co.uk/news/worldnews/africaandindianoce... [2] for more complete list, see: https://en.wikipedia.org/wiki/Iran_and_state-sponsored_terro...
It is only as a consequence of a wholesale ignorance of the reality of the Iranian regime, its government's motivating philosophy, and its brutal autocratic and dictatorial grip on power that someone could say what you've just said.
If this comes across as a sharp response it is because I'm tired of people giving Iran a pass by way of a false comparison to Saudi Arabia and/or misunderstanding or not taking the time in the first place to inform themselves about the realities of the current regime.
As an Iranian who has had family members and friends of my family imprisoned on trumped up charges, tortured and killed and their property seized (to then be charged for the bullet that killed them) it is unconscionable to give such a blood soaked regime a pass of any kind.[3]