What is the difference between the "scope" and the "on-topic" tags on most child metas?

Question

In most sites I participate, their child metas have simultaneously two seemingly similar tags: scope and on-topic (or off-topic, on-topic-ness, off-topic-ness). Is this redundant? If yes, shouldn't we automatically merge them together?

Explanation of the scope tag of MSE:

Use this tag when examining what is on-topic or off-topic, and why.

scope is used to define what is pertinent to discussion. Generally, the scope determines what the site is about. Issues arising from scope might have to do with whether a certain question is on-topic or not, but also can be used to evaluate whether an entire topic should be up for discussion (especially as it pertains to specific Stack Exchange sites).

Using this tag indicates that the question is requesting help with scope (normally as a specific use of a general topic), and answers should generally relate to the scope of the site and whether the topic raised generally relates. It also may be the case where a user has a question, but doesn't know where it belongs.

Explanation of the off-topic tag of MSE:

This tag is for questions regarding off topic questions, including whether a question is on topic and what to do with off topic questions.

Answer 1

I think they can be synonymized. One could argue that the second part of off-topic,

what to do with off topic questions

is not necessarily related to discussion about the scope of a site, but since the answer is just 'close them', retagging to vote-to-close would work.

Note that on Meta Stack Exchange, on-topic-definition is already a synonym of scope, and on Meta Stack Overflow, [on-topic] and [off-topic] already map to [scope] as well.

The problem with tag synonyms is that they are slow. Not many people visit the 'review queue' for these, and you need some score in one of the tags to vote on them. On Meta sites, it's even worse. I'm pretty active here, but somehow I just have a score of 3 in scope so I can't create or vote on a synonym. I've just suggested a tag synonym, you can vote for it here if you have a score of 5 or more in the scope tag.

Most synonyms are created by ♦ moderators nowadays, who can create them single-handedly. However, since this is an issue on all Meta sites, each with their own moderators, this will either require a massive coordinated effort, or one of the Stack Overflow employees (who have ♦ powers on all sites) needs to think this is a big enough problem to fix it at once.