Well, Luna, if you've been using this one "for years," I'd say it's about time you got it right.
The difference between the almost right word & the right word is really a large matter--it's the difference between the lightning bug and the lightning.
-Mark Twain, Letter to George Bainton, 10/15/1888
Over the yearss, the quote has become known popularly as the first way you have it:
The difference between the right word and the wrong word is the difference between lightning and the lightning bug.
The second version [that "makes much more sense"] seems to be a more modern day one:
The difference between the right word and the wrong word is the difference between the lightning bolt and the lightning bug (apologies to Mark Twain).
~from the personal webpage of Katie Roche
To paraphrase Mark Twain, the difference between the right word and the wrong word may be the difference between a fire and...a firefly.
~found at http://www.timezone.com/wwwboard/BB/messages/139.html