Liverpool received £75m for Luis Suarez after his move to Barcelona this summer and have signed nine players, spending around £130m.
Wales winger Bale joined Real Madrid from Spurs for £83.5m last summer and the London club splashed the proceeds on a raft of new arrivals, many of whom failed to make an impact.
Most recent Reds acquisition Mario Balotelli is set to make his debut at White Hart Lane on Sunday following his £17.6m move from AC Milan.
Rodgers said: "I think it is totally different circumstances, but obviously over the course of the coming years we will see.
"Spurs were a strong squad, had a top, world-class player in Gareth Bale and they will have their reasons for bringing in their players.
"For us, I think it is pretty obvious we were very low in terms of our numbers and that quality and depth.
"So, irrespective of Luis staying or going, it was something we had to do and I'm very glad we did it, because I look at the quality in our training and it has gone up a level.
"I see the hunger that the young players coming into the squad have given and the boost that has given the senior players as well."
Watch Liverpool's clash with Tottenham live on Sky Sports 1 on Sunday - coverage starts at 12:30pm.