Sparkle poops! I'd sell that as a bonus and charge extra!
Seriously, as others have said, both are inedible. But both are the same thing.
A 5g vial of disco dust costs about $4.25...that's $.85 per gram.
a 16oz jar of regular glitter on Amazon sells for $9.49...that's $.02 per gram.
Just use it only on decorations that the client understands are not meant to be eaten. For family, I've been known to lightly sprinkle a bit over a roughly frosted buttercream cake. Give it a great look and gives me the chance to tell them to look for sparkle poops the next morning. It always makes me giggle to think which of my relatives actually looks.