Hey, I can certainly answer these two questions for you but it would be based on the knowledge that I have.
There are 5 different segments into which cars are categorized. These categories are MPV, Hatchback, Sedan, SUV, and MUV.
An MPV a.k.a a multi-purpose vehicle is the one in which the engine, cabin space, and boot space are all in one compartment. (Maruti Suzuki XL6)
A hatchback is a car in which there are two boxes. One of the boxes holds the engine and the other holds the cabin space and the boot space. (Maruti Suzuki Alto, Maruti Suzuki Alto K10, Maruti Suzuki Swift, Maruti Suzuki Celerio, Maruti Suzuki Celerio X, Maruti Suzuki Wagon R)
A sedan is a 3 box car in which the engine, cabin space, and boot space are all separate. (Maruti Suzuki Dzire)
An SUV a.k.a sports utility vehicles are wheel drives that can be driven over rough grounds and huge strong bodies. In India however, some 2 wheel drives are also called SUVs. (Maruti Suzuki S-Presso, Maruti Suzuki Vitara Brezza)
A MUV is a multi-utility vehicle that is similar to an MPV in terms of being a one box car but it has a bigger build and can seat 6-8 people. (Maruti Suzuki Ertiga, Maruti Suzuki Eeco)
There is another classification based on the length, price range, and the engine type.
A Segment Cars (under 800 CC) - Entry Level Cars with Length under 3.6 Meter
B Segment Cars (1.2 Litre in Petrol n 1.3 Litre in Diesel) - Compact Cars with Length under 4 Meter
C Segment Cars (1.2 Lit - 1.6 Litre) - Mid Size Cars with Length > 4 Meter and Price from Rs. 5 Lac - 10 Lac
D Segment Cars (1.6 Litre - 2 Litre) - Mid Executive Cars with Length > 4 Meter and Price from Rs. 10 Lac - 20 Lac
D+ Segment (2 Litre+) - Luxury Cars above 4.5 Meter Length and price 20 Lac+