The PSLV (Polar Satellite Launch Vehicle) and GSLV (Geosynchronous Satellite Launch Vehicle) are two rocket launch systems developed by the Indian Space Research Organization, or ISRO, to launch satellites into orbit. The PSLV is the older of the two and the GSLV even inherits some of the technologies of the former in its design.
PSLV can launch only over a ton of payload into the orbit while GSLV is more powerful with the capacity to launch around 2.5 tons. GSLV uses cryogenic for its final stage while the PSLV does not use such fuels.
PSLV has six solid booster engines while GSLV works with four liquid engines. As far as the success rate is concerned, PSLV has proved to be more reliable with only one failure among the total of 18 launches so far. GSLV has been a failure with just one success from a total of 7 launches.