Well, yes, but that's the key difference in itself. Poetry must emit emotions by itself through its language. lyrics have the assistance of music to do so. Poetry is bound only by what sounds harmonious, lyrics must be harmonious with language and the music.
I think you can write both in pain or any sane state of mind anyway. Poetry, in my eyes, lets you send your message in anyway you want. Lyrics are essentially poetry that fits a melody. I'm sure you can compose a melody for The Raven is you wanted to.
I'd say making lyrics are much harder because you still have to convey your message while fitting the time signature of the music you're writing.