Wood burns best on a bed of ash so wood-burning stoves usually have a flat bed on which to build the fire and no ashpan, with air for combustion coming from above.

A multi-fuel model gives you the option of burning solid mineral fuels (coal etc) too. They have a “riddling” (raised) grate, as smokeless coal requires combustion air from underneath the fire, and an ashpan to collect the cinders but also have airwash so that they can also effectively burn wood. The riddling grate allows the ash and cinders from smokeless fuels, anthracite or peat/turf briquettes to be riddled into an ashpan below, maintaining the primary airflow through the fuel bed and, hence, creating the optimum conditions for efficient combustion of those particular fuels.