OTG is Oven-Toaster-Griller.It is a mini oven which can be used to bake cakes,toast bread,and also reheat small amounts of food.In this,food takes longer time to cook,compared to microwave. OTG has heating elements both on the ceilng and the roof of the oven.You have the choice of either one or both coils to heat your oven. For grilling,you need to heat the top coil and for normal baking,you need both coils to be heated.
Microwave oven cooks food with the help of moisture.so,you cannot bake all cakes in it,since it does not brown the foods,hence you can only make certain cakes,the recipes of which are specially formulated to suit the microwave's cooking process.
Microwave comes in three basic types - basic microwave, microwave with grill and microwave with grill and convection.Microwave with convection and grill comes closest to the OTG and can almost do everything an OTG can.
A microwave oven uses microwaves to heat food. Microwaves are radio waves. In the case of microwave ovens, the commonly used radio wave frequency is roughly 2,500 megahertz (2.5 gigahertz). Radio waves in this frequency range have an interesting property: they are absorbed by water, fats and sugars. When they are absorbed they are converted directly into atomic motion -- heat. Microwaves in this frequency range have another interesting property: they are not absorbed by most plastics, glass or ceramics. Metal reflects microwaves, which is why metal pans do not work well in a microwave oven.
An OTG(Oven Toaster and Griller) uses a heating filament as used in a water guyser or ordinary room heater to cook food. It adds direct heat to food to cook it. A Micro wave oven cooks food by generating friction between the molecules of food item, by producing microwaves. The food cooked in Microwave oven maintains its Nutrition value in comparison to an OTG.
Though an OTG is slow but the price of an OTG is much less than a microwave oven.
You can heat food safely in a microwave,but if you are not an enthusiastic home baker,all you need is the microwave oven.If you want to bake cakes and cookies,OTG is your best bet.But if you buy the OTG,you need not buy a toaster, and a grill.that saves you some money right away.