Radiation is when heat is emitted as invisible light. These rays travel through the air until they hit a material which absorbs them. This material will become warmer as a result.
This type of heat is ideal in a room with a high ceiling, in buildings with plenty of draft, or simply if you are looking for rapid direct heat from your fireplace.
When arranging furniture and any other objects, you should remember that it can be extremely hot next to the fireplace. A free-standing heat shield can be used to prevent heat being radiated in particular directions.
Convection is when the air around the stove becomes warm, expands and rises. If the stove has a convection chamber, the air between the stove and the plates heats up more quickly. The heated air will rise and transport heat around the room.
The hot air gathers under the ceiling and it will be possible to blow this down towards the floor using a ceiling fan. Convection takes a little bit longer to heat up the room, compared with radiation.