What does Control mean?
When a player is said to control a permanent, said permanent must have it's choices made by the controlling player. The controlling player chooses when/if to use it's activated abilities, (if it's a creature) when/if it will attack, and when/if to sacrifice the permanent among other things. The controlling player doesn't necessarily have to own the card. Whenever you cast a permanent, it goes under your control.
Owning the card depends on who literally owns the card when the game is over. There are many effects and spells which can transfer control of permanents from one player to another. Red enables players to gain control of permanents or creatures for a short amount of time, and blue enables you to gain control of creatures for the rest of the game unless they are returned to their owner's hands or destroyed, in which case they are put into their owner's graveyard. However, the owner is not always the controller.