Pellet grills/smokers burn hardwood pellets for heat, and to some degree, flavoring of the food. They burn a small, hot fire with their pellet fuel, but charcoal cannot be used to fire them, unless it were broken-down in size (approx. 1/4"-5/16" diameter)...feeding issues and erratic temperature control would likely result. A charcoal smoker uses charcoal briquettes or hardwood lump charcoal for heat. With both, you can add smoke woods for smoke flavor. Many use a smoke generator of some sort for their pellet smokers, but I'm sure you can achieve smoke from them without the use of a smoke device. With charcoal smokers you simply add smoke wood chunks near or among the briquettes for smoke flavor.
I would suggest you find a source for pellet fuel, briqs and lump, then do price comparisons over charcoal briqs or lump...you'll need to know about how many lbs of fuel per hour will be used with the pellet smoker vs a comparable charcoal smoker...that is if a budget is of concern...if fuel cost is not an issue, then disregard. I would research for common problems with the pellet smoker, though...some can have problems with reliability, as they are an electrically controlled/operated device.
Hope this helps you to pick your poison...uh, I mean...smoking toy...err, um...cooker...LOL!!!
Eric