This morning, we discussed in chat how the current comics tag seemed to be mainly aimed at American comics (read Marvel/DC, even if it's obviously not limited to that). The discussion starts here and goes on for quite a bit of time.
The thing is, the current tag, or at least its description, is quite broad and may overlook some existing genres.
The Franco-Belgian comics genre goes a bit beyond the "simple" comics as we usually understand it. It is both a matter of content and shape, and the behind-the-scenes, but the latter is probably not the most relevant part for this question.
Long-story short, Franco-Belgian comics were once defined by the author Franquin1 as "everything that is neither American or Japanese". To quote SQB, you can think of it as "halfway between US-style super-hero comics and graphic novels". Not the same stakes, broader range of characters and stories, and the most "visually striking" aspect would be the paperback format, I guess.
As per this point, I should admit that while the idea is kind of clear in my mind, I'm not that great at actually expressing it - put that on having been raised with the concept. I'll be more than happy to edit this post following questions asked in comments though, to make my point clearer.
Some reading about what is the genre, and how it actually differs from the general comics2: here, this Quora thread and this article, though the latter rather addresses the behind-the-scenes; I'd recommend to focus on the "The Format for Success" subsection.
Hence, the Franco-Belgian comics appear to be a sub-genre of comics just as much as mangas are, and there's a tag for those. (to poke at someone in chat, it's not just about the reverse-reading order, black & white coloring and exaggerations with lines :) )
With regards to what has been said here and in chat, and what will be said in the discussion comments, should we have a tag for those comics? And if so, what should its name be? (see my answer for more details on that)
1 I think it was Franquin, but I may be mistaken. I'm still looking for the source, but if anyone speaks French and is willing to look for it, I'm 99% sure I heard that in a Tac au Tac TV show from the 70's-80's.
2 This might come off as restrictive, but given that a lot of the questions in the comics tag refer to American works (Marvel/DC mainly), I'll just stick to saying "comics" as such.