Sip is a systematic way of investing your money in mutual funds. You can invest every month or quarter or year, it depends on the plan you have chosen.
SWP allows you to withdraw any amount of money from a mutual fund whenever you want. Funds are generally withdrawn either to re balance the existing portfolio by investing in other funds or for meeting personal expenses.
STP is an automated way of moving (transferring) money from one mutual fund to another. This plan is chosen when one wants to invest a lump sum amount but wants to avoid the marketing-timing risk.