In Matthew 5, when Jesus says that he did not come to abolish the law, but to fulfill it, he then says that whoever relaxes the least of the commandments will be called least in the kingdom of heaven. Does the Church teach that some will be greater in heaven than others, or does it teach that heaven will be equally perfect/great for everyone?
Everyone who makes it to heaven will experience perfect happiness to the degree to which he is capable of receiving it. Those with greater capacities to love will receive more, but all will be perfectly happy according to their capacity.
As an analogy, you have a shot glass and you have a stein. When you fill them, both are full; but the stein can hold more liquid than the shot glass. In the same way, those who make it to heaven will be filled with all the love they can hold.