Neither of those terms are quite interchangeable though. Everybody has low energy days, that's relatively normal. But the word spoons is a shorthand for explaining a precious, and much more finite resource, as a way to distinguish the experience for disabled people.
I'm sorry, are you trying to argue that spoons aren't a vital, nor precious, resource for disabled people? Because I disagree vehemently. Please go and read Christine Miserandino's original post:
The fact you can't respect that I ran out of spoons for arguing the point, kind of just proves my point that you don't understand the term, doesn't it?
Here I am, after sleeping and recovering some spoons. That are precious, that I still don't want to waste on changing your mind, when you're clearly not willing to understand.