My apologies too... I hadn't seen all the replies re 'mark up' before posting. However, it seems the two contenders are at an impasse.

All I know is that if I am running a business and need to make a profit, I know I need to mark up x% from my raw cost.
But someone looking at my company and knowing my revenue can use my Profit Margin (y%) to see how much profit I make.

When my kids ran a neighborhood fruit and drink stand, I fronted the startup costs but then they had to support themselves from thereon (cups, lemons etc), thus learning fundamentals of cost v profit. They did OK! My ROI was seeing them have fun and making some money and letting me have an occasional free drink (which I treated as a dividend and kept under $10 in value to avoid the 1099 - I think they wrote it off as a marketing expense). ;-)

And, yes, I know it is MUCH more complex than that!