RD and SIP both work on the principle of setting aside some money to invest each month. However, the nature of the investment and the growth of money differ completely. The returns are thus significantly different from each other.
The funds invested through an SIP grow depending on market-linked returns and help accumulate wealth for long-term goals while spreading market risks and losses incurred over a long horizon. An SIP instils discipline in financial planning and helps accumulate a part of ones income to leverage for corpus building. A small monthly portion of ones income can thus generate a substantially bigger amount over time.