While systematic withdrawal plan faciliates regular withdrawal of a fixed amount from the scheme at a regular frequency.
A systematic transfer plan is a disciplined way of shifting part of investors' current investments into other schemes, thus providing diversification.
Flex STP is a facility proposes a varying STP amount in line with changing market scenarios. Thus when the market is down, it increases the value of your STP and when the market is up, it reverts to the pre set STP amount.