Bush 41 Forced Iraq to a Ceasefire in 100 Hours. Under Bush 43 the U.S. Took 22 Days to Capture Baghdad.

Iran is a much bigger country than Iraq. Population of about 90 million. Iran has a far more powerful military than Iraq.
Iran is built like a natural fortress, with extensive ranges of mountains. They have dug deep tunnels which house a fleet of thosands of drones.
Iran controls the strait of Hormuz. They have laid mines on the sea bed which rise to blast the hulls of ships and sink them.