The only difference that exists between these 2 variants of the Tata Safari is that the 4x2 one is a 2 wheel drive whereas the 4x4 is a 4 wheel drive vehicle.
Four-wheel drive, 4WD, or 4x4 ("four by four") is a four-wheeled vehicle with a drivetrain that allows all four wheels to receive power from the engine simultaneously. This feature is often, but not always, included in the broader sport utility vehicle (SUV) category. Used mostly for off-road driving & rugged terrain, powering all four wheels provides better control on many surfaces, and is an important part of rally racing.
And as far the 2.0L or 1.2L is concerned, that specifies the engine size. The bigger the capacity in litres the bigger & more powerful the engine is. So what a 2.0L engine can give you is loads of more power & acceleration than the 1.2L engine but what you lose in the bargain is fuel efficiency which is better in smaller engines. The more the power in the car the lesser will be the fuel efficiency. There exists an inverse relationship.
I hope that solves your query arvind !!