A Value Averaging Investment Plan, or VIP, works differently from a regular SIP. Instead of investing the same fixed amount every month regardless of market conditions, you set a target growth rate for your portfolio's value, and then invest whatever variable amount is needed each month to hit that target — investing more when markets are down and less (or even redeeming a bit) when markets are up.
In theory, this can improve on simple rupee cost averaging, since you're systematically buying more when prices are low and less when prices are high, in a more deliberate way than a fixed SIP does automatically. In practice, it requires more active tracking and calculation each month, and the variable investment amount can make budgeting harder, which is why fixed SIPs remain far more popular among everyday investors for their simplicity.