Borussia Dortmund have more appeal but less financial power than Manchester City, CEO Hans-Joachim Watzke told reporters.
Dortmund have lost three key players this summer, with Ilkay Gundogan opting to join City, Mats Hummels heading for Bayern Munich and Henrikh Mkhitaryan joining Manchester United.
Earlier this week, Borussia coach Thomas Tuchel acknowledged there are clubs "above us both economically and in prestige," but Watzke said those clubs were in a very select group.
"Maybe five clubs have more appeal and financial power than BVB," Watzke said at Dortmund's first preseason training camp in Austria.
"I think it's safe to say that we have more appeal than Manchester City, but you add the financial power to it and it's a completely different story."
Dortmund earned more than €100 million through the sales of Gundogan, Hummels and Mkhitaryan and have already invested around €60m on six new players, but their transfer activity is far from over.
"We will do a few things [on the market], that's clear," Watzke said.
Dortmund have brought in Marc Bartra and Sebastian Rode, both 25, from Barcelona and Bayern respectively, as well as Portugal international Raphael Guerreiro, 22, from Lorient, 19-year-old Ousmane Dembele from Rennes, Emre Mor, 18, from Nordsjaelland and Mikel Merino, 20, from Osasuna.
Watzke admits the younger players are likely to need time to adapt, saying: "We might be off to a difficult start."
Dortmund are also closing in on Wolfsburg forward Andre Schurrle, and kicker reported on Thursday that they are back in the race to sign Bayern outcast Mario Gotze.
In defence, Neven Subotic is likely to leave for a Premier League side, and the Serb could still be replaced by Bayer Leverkusen centre-back Omer Toprak, who confirmed on Wednesday that he wants to make the switch to the Westfalenstadion.
"I want to move on," Toprak, 27, told Kolner Stadtanzeiger. "I have told the club what I think. There was a bid from Dortmund, which was rejected by Leverkusen. I am here, and that's all I can say."