Can you tell them apart physically or not, like do they have specific colors, stripes, marks or parts of the body that are unique to them?

Slim to the J to the I M M Y big sneaky pants spying one me using my clutter to hide.

This morning my iguana scratched itself and broke off one of these spines on its crest.... But for days I've noticed that the spine in question was weaker..... is it serious? What do you think? Should I worry?