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

From The Elements of Style by Strunk and White in Chapter 4 – Words and Expressions Commonly Misused:

“*Flammable*. An oddity, chiefly useful in saving lives. The common word meaning ‘combustible’ is *inflammable*. But some people are thrown off by the *in*- and think *inflammable* means ‘not combustible.’ For this reason, trucks carrying gasoline or explosives are now marked ‘flammable.’ Unless you are operating such a truck and hence are concerned with the safety of children and illiterates, use *inflammable*.”