The pellet stoves are hugely different from even the most modern woodburner.
They have a sealed combustion chamber into which the pellets are fed automatically from a large hopper. And I do mean large - if you imagine your average 1000-litre oil tank, quadruple that size for the same amount of wood-pellet energy.
The are extremely efficient and are ideal as the basis for a domestic heating system. They don't have the aesthetic appeal of a traditional woodburner or an Aga, however.
That said, pellet stoves are far greener and, if you have plenty of room for the hopper and good access to the fuel, they are far better than oil, LPG, coal or traditional wood.