I'm trying to find an idiom for a poor substitute. One that comes to mind is Mark Twain's purported remark: “The difference between the almost right word and the right word is really a large matter. ’Tis the difference between the lightning bug and the lightning.”
I’m looking to describe something that intrinsically falls short – not a failing of someone or something in a particular instance. The metaphor should mention two persons or objects (like lightning and lightning bug), one of which falls almost ludicrously short.
Are there other, colorful metaphors that carry this meaning?