City have been impressive in Pep Guardiola's second year in charge and his team have drawn comparisons
with Arsene Wenger's all-conquering Gunners of the 2003/04 season.
However, Campbell feels there is a lot of money involved in football now to compare the two teams.
"It's a different time," he told Sky Sports. "The difference now is the money is on a different level to buy players. You had to be a bit more clever with players back then, you couldn't make too many mistakes and then say OK let's buy some more players.
"That's the difference with Man City, they can say it hasn't worked out and then buy two or three players at Christmas, it's just another level. They are in two different eras and two sides playing great football."
The Citizens in the running for a treble this term and can also clinch the Premier League title on Saturday if they beat neighbours Manchester United.
Campbell added on City: "It's beautiful to watch - the movement and the ability. Everybody is moving, working, inter-linking and making the pitch wide. You have the keeper playing like Franz Beckenbauer at the back spraying the ball around. He can pick the furthest man and drop it on his toes.
"It's all about possession - when you haven't got the ball we are going to tire you out and pick you off. Pep Guardiola allows the players to do that and have confidence in the players and have the ball in tight areas because that's the way to retain possession, open you up and then pick you off.
"They have got great forwards and midfielders and because they have possession that allows the backline not to get exposed. The backline can cope with one or two situations or breaks, that's fine.
"Before it was six, seven, eight or nine in each half, which puts pressure on the defence. Now they set up to retain the ball and tire the guys out then you won't have many chances to attack, it's great football."
