What are the parameters of determining the launch capabilities of a rocket? Also, How does ISRO's GSLV Mark III fare against rockets like N-1, Proton, R-7 etc?
In the list of current operational launch vehicles, this is how GSLV stacks up. This is a comparable list, to compare it to N-1, Proton, R-7 would be an apples-to-orange comparison.
Vehicle Deliverable Payload to GTO (kg) 1. Long March 4B/4C 1500 2. Long March 3A 2600 3. Soyuz STA-A/B w/ Fregat 2810/3250 4. GLSV MkIII 4000 5. H-IIA 5950 6. Delta IV 6390 7. Atlas V 6485 8. Falcon 9 FT 6500-8300 9. Ariane V 10850
What are the parameters of determining the launch capabilities of a rocket?
The main parameter is "payload to orbit", but you have to specify which orbit you're using. In the answer by ASRI_306, 'payload to GTO' is used (i.e. geostationary transfer orbit). Strictly speaking, that's incomplete because there is more than one transfer orbit. 'GTO 1500' means a transfer orbit where the payload has to add 1500 m/s of delta-V to get from GTO to geostationary orbit, GTO 1800 is also used by some manufacturers.
Similarly, if you specify low Earth orbit (LEO), you have to specify the altitude.
Another method is to specify the launch energy. This is more flexible, but requires a bit of calculation to apply it to a specific mission.