What are the types of robots because of their purpose, capacity, size etc.?

The theory mentions several types of robots classified into different parameters, including based on the geometrical properties, the construction of a kinematic unit, or due to the application area. In our business we deal with industrial robots. That group includes: welding robots, painting, assembly, to carry a load and palletizing, materials processing, laboratory and to work with hazardous materials.
Used in our company, industrial robots are those by which we can carry heavy loads, eg. 50 kg bags, place them on pallets (or remove them), and robots used for pick and place applications. Articulated robots have a load capacity of 7 to 1200 kg. Delta robots used in applications such as pick & place may up capacity of 1 to 12 kg. Palletizing robots have a load capacity from 50 to 700 kg. An important parameter is also the maximum operating range which they can have. For small delta robots a range is from 420 to 1,350 mm, while palletizing robot can reach a distance even more than 3,5 m.

Fanuc robotics