TEHRAN — President Mahmoud Ahmadinejad arrived in Cairo on Tuesday as Iran’s first head of state to visit Egypt since the two nations ended diplomatic relations in 1980, another sign of the regional shifts triggered by the Arab Spring.

But although the countries’ ties have thawed since the overthrow of Egyptian autocrat Hosni Mubarak, key differences — including opposing views on the conflict in Syria — make the prospect of fully restored relations distant.