One difference between a pellet stove and wood stoves/fireplaces is that the majority of pellet stoves require electricity in order to operate. This electricity is needed for a small electrical device in the stove that controls the flow of pellets into the stove, where they are burned. Some models even include a thermostat.
While there is a drawback of having a stove that uses electricity (no heat if the power goes out). Having a thermostat is a huge benefit that you won't see on other stoves or on fireplaces.