Stressing Models

Can someone please explain to me the difference between Factor push analysis and Max Optimisation?

Am I write in thinking, FP pushes all the factors to the most disadvantageous combination of possible circumstances while MO mathematically optimises the variables to give the maximum loss…

And worst case scenario - is a more realistic worst case scenario that could realistically happen

Is my understanding correct?

factor push - is stressing ONLY ONE input at a time.