Why do “flammable” and “inflammable” mean the same thing, or is there a difference?

Question

Edit: SERIOUSLY, THANK YOU—

BTW my confusions stems from them having the same meaning online

Flammable: “easily set on fire”
Inflammable: “easily set on fire”

Definitions from Oxford Languages

In: Other

Answer 1

This has caused serious fires in India where English is not the first language. People thinking that “Inflammable” meant fire retardant.

I read some guidance in the early ’90s that made that point.