Do we find them on topic? There are sites out there dedicated to do this comparison and are able to visually display it a lot better than we ever can.
Perhaps a single canonical explaining how to compare licenses, and link everything to that?
I agree that before we flood this site with questions all asking about what's the difference between this and that and that and this, that we should instead educate the general public, to make their own judgements and decisions on comparing licenses. Therefore, I'm in favour of having a large answer to detail how people can compare.
However, I disagree that we should make these sorts of questions off-topic, as people would get the chance to get a second opinion or get additional information that they may not have known before.
I don't see why they would be off-topic. Licensing is relevant to open source.
“What's the difference between <license A> and <license B>” is too broad. But “How do <license A> and <license B> handle this specific aspect” would be a suitable long-tail question.
I think you're correct that other sites can do the job better than we can, when it comes to comparing two licenses in their entirety, and I like your idea of building a canonical question about comparing licenses.
Having a canonical question is better than declaring these questions de facto off topic because it allows us to use our best judgment in deciding when to close as a duplicate of the canonical question, and when to recognize that an issue is worth addressing separately.
In some cases, the two licenses may be so similar, perhaps because they have a lot of shared history, that a specific question asking how to distinguish them would be reasonably scoped. The general, canonical question shouldn't get bogged down in the details of a particular tricky comparison like this, except as necessary to illustrate the general solution. So it's good to have them separated.
A prototype question of this format was well received and voted as the top question when this site was still in Area51 proposal. Therefore, I think that these questions has their potential and shouldn't be restricted.