What's the difference between a hair dye and hair gloss treatment?

I understand that dying is supposed to be damaging to your hair, at least a little bit.





But what about getting a gloss -- does that have any negative effects on your hair?What's the difference between a hair dye and hair gloss treatment?
Dye obviously dyes your hair, whereas a gloss treatment seals in your hair actually protecting some damage and breakage. There aren't any negative effects as far as I'm concerned. Gloss isn't permanent though.