difference in plan and forcast curve

plan curve uses your baseline dates, and hence does not change (unless you rebaseline)

forecast curve uses your latest update dates. Input the forecast data each week as the schedule is updated.

Thanks for your reply!

but if I update each week with new data, so what's the difference between actual curve. By the way, all our curve was formed by completed work quantities.

actual and forecast are both parts of the same curve -actual part of it for the past, forecast for the future.

Plan Curves represent the baseline plan

Forecast curve will project the plan of remaining work in light of till date progress and future outlook.

i.e. forecast curve = actual curve + plan for the remaining work