Redknapp, whose team face Aston Villa on Sunday, said: “What have Man City done to get into the top four or maybe win the league?
“They have not suddenly developed a youth policy. They have gone out and bought fantastic players, that is what they have done.
“That is the difference. They can buy Yaya Toure. They can play players costing £250,000 a week.
“It is a different world, they are entitled to be up there.
“At the start of the year, if you looked at it, Arsenal, Man United, Man City are absolute certainties, so you are playing for two places really.
“Realistically, where are we? Fifth or sixth, maybe? That would be my honest opinion.
"I wouldn’t say we have over-achieved if we finish fourth, but we will have done very well.”