The big difference between tea bags and loose leaf teas are quality, most tea bags are full of 'dust'. The stuff left over from processing loose leaf... not all, of course, but the basic ones. The flat tea bags are the usual ones, if you find 'pyramid shaped ones, those are better as the leave room for tea expansion. I do have several brands I use regularly...like Traditional Medicinals, I love their 'Throat Coat! It is just the thing for a sore throat.
Loose leaf tea is a better choice as it is whole leaf and herbs. The problem most folk have is with brewing it...forget the nasty tea balls! They are difficult to open and close and messy to boot! I recommend using a tea infuser...it is a small basket with a sieve like bottom, this makes it easy to fill and empty.