Prod strategy

What is Difference between Strategy 10 n 40, plz tell me in detail as i know basic difference but on which point any production strategy out of 10 n 40 will be selected for production.

n if i assign 10 to one material for planning n production n meanwhile i change it to 40 from 10 then what will happen

i want to make clear selection logic n difference between 10 n 40