Teabag tea is cut up much much finer than looseleaf tea. Whereas looseleaf is identifiable bits of leaf, the stuff in teabags is ground up into a powder. They do this deliberately so that it will brew more quickly, and a good cup normally takes 3-5 minutes.

Looseleaf tea takes longer to brew, which is why you can brew a big pot, pour and drink one cup, and then come back for a second that's been sat on the leaves without it tasting like industrial chemicals.