I was taking a quote off the link from the Blue Star web page https://www.bluestar-forensic.com/pdf/en/Watkins_Brown_luminol_BS.pdf
It doesn't have comparisons for metal surfaces, only the reaction that both products produce when sprayed on a surface cleaned with bleach. (It;s under the caption "Clean Up")
(BTW: It looks like Blue Star is a better product than Luminol, lol!)
1:20:45 of the video, he describes what he saw and what it means and what it could be, he says any number of compounds, could be soil, must (as in musty, but this is not a real word I don't think lol but that is what he said)