City are coming off back-to-back Premier League titles, while Liverpool are 14 points clear with a game in hand this season.
Mourinho was appointed Spurs head coach in November, and his side are battling in eighth in the table.
But the Portuguese tactician said they could not be compared to City and Liverpool, although he has no complaints.
"Come on, it is what it is. We cannot have a squad like some other teams. It's not us," Mourinho said.
"I was watching Man City [against Aston Villa] and I looked to the bench – [Raheem] Sterling, Bernardo Silva, [Ilkay] Gundogan, [Nicolas] Otamendi. You know?
"Liverpool, you see the team, you see the bench. And they have injured [Joel] Matip, [Dejan] Lovren, [Naby] Keita, Fabinho.
"I'm not jealous, I have an amazing job, but they are different jobs. This is a different club."
Mourinho suggested the job at Spurs was his most difficult since he was at Porto, where he took over in early 2002.
"It is the second time I get a team mid-season, just the second time," Mourinho said.
"The first time was also not easy because it was the end of a team, the end of an era. It was an era without titles.
"Porto was not winning but it was the end of... I don't want to say of a generation but it was the end of a team in the end of a season.
"Twelve players out, twelve players in, start everything from the beginning. Forget the good things of the past, forget the bad things of the past and let's build from new.
"That is my experience in Porto coming in the middle of the season."