PSLV and GSLV are the two rocket launch systems developed by ISRO.
PSLV stands for Polar Satellite Launch Vehicle and GSLV stands for Geosynchronous Satellite Launch Vehicle.
PSLV is used to send satellites to the lower orbits. whereas, GSLV is used to send satellites to the higher orbits and also higher loads.
Of the two, PSLV is of the former origin.
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.