These are the two reserve ratios of RBI mandatory for commercial scheduled banks in India.
Statutory liquidity ratio.i e., SLR is the minimum percentage of total deposits with the banks that they have to maintain in the form of cash , gold or approved government securities.
Cash reserve ratio i.e CRR is the ratio or percentage of total deposits of bank that they must keep as cash reserves with RBI.
While SLR is to be maintained with the banks only, CRR is to be kept with RBI. Banks do not earn any interest on CRR while they earn interests on SLR. CRR can be maintained only in terms of cash.SLR can be maintained in terms of cash, gold and govt. approved securities.
Today announcement is the example of same where repo rate and reverse repo rate is been reduced.