The Gunners boss has overseen big progress since taking over at the North London club in 2019 - although has not won silverware since lifting the FA Cup in 2020 - and Amorim doesn't think he would be able to survive such a drought at Old Trafford.
Amorim, whose team take on Arteta's Arsenal in the Premier League on Sunday (09.03.25), said: "I will not have the time Arteta had.
"I feel that. It's a different club, I think it's a different club. I think in that aspect the way Arteta dealt with that is an inspiration for everybody but I will not have the time like Arteta had."
The Red Devils manager is concerned about how his injury-hit team will fare against Arsenal as the game is sandwiched between their vital Europa League last 16 tie against Real Sociedad.
He said: "We need to survive on Sunday.
"The team was so tired in the last 20 minutes [of the first leg against Real Sociedad]. We have to prepare for Sunday and think about this important game for our season on Thursday (13.03.25).
"We are trying to see all the players who are fresh and who are not in danger of getting an injury. Even with that we have to risk a little bit but we have to be competitive on Sunday."
The match at the weekend will see United fans stage a protest against the club's ownership before kick-off but Amorim says his team can only influence matters on the pitch.
He said: "For everybody in our club it's a really tough moment.
"It's everything at the same time. The only thing I can do is and our players can do is perform well and win. People have the right to protest."