Burgers are round disks of something that people eat between sections of a bun that has been sliced in two.
Meatburgers: Most Burgers are made of unhealthy types of meat that nobody would want to eat any other way. Most Burgers are greasy and sticky because they have too much unhealthy saturated fat in them. After all it's cheaper to produce burgers with saturated fat that will make your customers satisfied. There's also likely to be too much salt They're certainly made from processed meat and too much processed meat is unhealthy. Some burgers have a bit of salad on top so people won't realize how unhealthy they are. Others have cheese.
Vegeburgers: Vegeburgers are perhaps healthier than meat burgers as they are made of vegetables, usually plenty of beans or other healthy pulses but vegeburgers are also greasy so there may be unhealthy meat fat in them even if vegetarians imagine they're OK. If you want healthy burgers make them yourself so you know what's in them. Alternatively buy them in a packet but check the contents and nutritional information first.