Unless the definition in the wiki for headphones is changed, the tag currently doesn't cover earphones.

It has always covered earphones too.

blooregardo said:
It has always covered earphones too.

Then it seems that the second sentence contradicts the first one, as it reads:

The two speakers are held in place by a strap over or behind the head and usually cover the entire ear.

But earphones usually isn't.

P.S. Looks like the original version was copied from those xbooru that have a separate tag for earphones? Maybe some sort of clarifications can be made in the wiki description?

Yeah, our tags usually have a broader use but I guess another mod could help throwing more light on the subject.