Let me make this as simple as I can as you are seemingly to struggle with this incredibly basic concept. I swear to God if you can't pick this up then you're not even trying.
Sheikh Mansour owns Manchester City lock, stock. 100% share ownership. The investment into the club is derived from his personal wealth.
Etihad Airways is owned by the
Government of Abu Dhabi just like General Motors were owned by your Government
or these other 146 airlines that are Government owned.
A Government consists of many different people in many different roles. The
UAE Government has somewhere in the region of ~500 employees across its various ministries and departments. One of those 500 people is Sheikh Mansour, who is Joint Deputy Prime Minister which is mainly ceremonial and also runs the Department of Presidential Affairs which looks after protocols for the President.
You are suggesting that Manchester City and Etihad are owned by the same people. This is because Etihad are owned by the Abu Dhabi Government, which is the Government of the Emirate, and Sheikh Mansour is from that Emirate but works for the Government of the UAE which is the country.
This is like suggesting that because the state of Hawaii owns Honolulu Airport and Barack Obama is the US President, than Barack Obama actually owns Honolulu Airport.
As I pointed out earlier, the reason you have gotten this wrong is because it's an Arab country and you couldn't give a shit about the details because all Arabs are the same person to you lot. Thanks, and bye bye.