Freestanding microwaves come in 2 main types now. The first being a 'Microwave with Grill'. These are a standard freestanding microwave with the added benefit of a grill feature so that you can have all your normal microwave uses (such as reheating food, cooking a jacket potato or soup etc) but with the added grill allowing you to make dishes such as cheese on toast which you would normally need to cook under the grill.
The second type is a 'Combination Microwave'. These combine all the benefits of a Microwave with Grill with the added benefit of convection heating which allows you to roast and brown food in the same way a fullsize oven would.