Differences forecasting using demand management and replenishment planning ?

What is the differences forecasting using demand management and replenishment planning ?

Hi experts,

Our clients want to have forecasting and supply planning at sub inventory level. Since subinventory level planning only available using replenishment planning and considering replenishment planning can also generate forecast, what is the differences using forecast using demand management and replenishment planning ? We want to see the supply planning for each Subinventory within the forecast generate from ORG1