A good explanation, and further, many times a good analogy relies on the things being very different in every way except for the one way it intends to emphasize

A good explanation, and further, many times a good analogy relies on the things being very different in every way except for the one way it intends to emphasize. An analogy is often a way of saying: "Let's focus on this (often very abstract) aspect of interesting similarities. Yes, you can easily point out many other dissimilarities. That ease means I'm not talking about those aspects, so if we understand each other those don't even have to be mentioned."