ISIS in Iraq

The Iraqi army is about to attempt the liberation of Mosul, Iraq, from ISIS. Is ISIS any different now that it was previously when it was labeled the Sunni insurgency or a few dead-enders by Donald Rumsfeld when he was Secretary of Defense? The name of the opposition to the government of Iraq changes over time, but I suspect that the composition of the opposition and the reasons for fighting remain the same. The Shia government of Iraq continues to oppress the Sunni minority who ruled Iraq under Saddam Hussein.