Is there a specific word for this kind of comparison?
"Michael Jordan was to basketball what Messi is to football."
What is the best noun to describe this kind of comparison?
I feel as though I've come across a more specific word than 'metaphor' or 'analogy' in the past, but, I can't think of what it is.
Phrased like that, the statement you're making is an analogy.
On the other hand, if you rephrase it as Messi is the MJ of football or the other way around, you would be using a metaphor.