Ans 1: (Master Answer)
SLV that stands for Satellite Launch Vehicle, was a project started by the Indian Space Research Organisation (ISRO) and was headed by APJ Abdul Kalam in the early 1970s, to develop the technology needed to launch satellites.
PSLV (which stands for Polar Satellite Launch Vehicle), GSLV (which stands for Geosynchronous Satellite Launch Vehicle) and ASLV (Augmented Satellite Launch Vehicle) are expendable satellite launch systems operated by the Indian Space Research Organisation (ISRO). The difference between all three systems lies in the difference in their payload capabilities. For example: In case of ASLV with vehicle weight of 41 tons, can launch payloads of 150 kgs into space upto an orbit of 400 kms. While in case of PSLV with vehicle load about 295-320 tons, can launch payloads upto 1678 kgs in sun synchronous orbit of 622 kms. And in GSLV with vehicle weight of 415 tons, can carry upto 5000 kgs in orbits of 550 kms.