‘ISIS’ vs. ‘ISIL’ vs. ‘Islamic State’: The political importance of a much-debated acronym

Islamic State of Iraq and Syria or Islamic state of Iraq and the Levant, I wondered why they call different names or people refer to it as daesh also. What's interest is that people seem not to generally want ISIS in the US yet ISIS itself includes people from Syria and they want to bring people from Syria that can't be vetted here titled under refugee status. The terrorists have expanded their network all over so it would be naive to say they are just from Iraq or Syria but the proof is in the pudding. I know American muslims from pakistan for example and they are americans who aren't ashamed of who they are like the media portrays muslims to be. Muslims who have a problem with america - concern me and that's my opinion