The former Bayern Munich striker has netted 11 goals in Serie A ever since joining Lazio in the summer.
Ibrahimovic, on the other hand, has collected a total of 15 goals in the league so far, but Reja thinks that the Germany international makes a vital contribution to the team as a whole.
"Ibra is more spectacular, he searches for opportunities to shoot," he told Lazio Style Radio.
"Klose brings a lot more to the team, he works for the team. He is a smart player, a true squad man."
Reja went on to praise Massimiliano's side before both teams clash at the Stadio Olimpico on Wednesday.
"We are still growing, but in any case Milan are a great team, both technically and physically," he concluded.
Lazio are currently seven points behind AC Milan in the Serie A table.