It's because Manchester City has an unlimited funds to buy dreams manager and player, while in Liverpool the owner is stingy, even though they sign a good manager, but they didn't give funds to buy dreams player.
If Liverpool give as much as Manchester City did, Liverpool will become very strong rival and they might able to win many many trophies.
Naturally Manchester City spent a lot of money to build the squad to be stronger because indeed they have not achieved success as has been obtained by Liverpool. Club Manchester City voters also have a number of well -known businesses and he is a person who is quite influential with unlimited wealth, so to buy any player is not a big problem for him. In contrast to Liverpool owners because he cannot allocate large funds like Manchester City, so they continue to rely on existing power.
What Manchester City did had given results where in the previous season they managed to lift three titles at once in one season, so that their struggle was not in vain and the large funds spent were paid thoroughly by the achievements they got. This season Manchester City is also still in the race for titles with Liverpool and will be far more interesting when this competition continues until the end of the season.