[url=https://example.com]link text[/url]
[link text](https://example.com)
>Markdown is a lightweight markup language
Clearly in over my head on this, I'm just going to stop using the term altogether.
BBCode was used on old internet message boards. You'd write something like [b]text[/b] to get bolded text, [i]text[/i] for italics, [img] to embed images, etc. BBCode tags (like [b]) mirrored simple HTML tags usually: since message board posters weren't really trusted, allowing regular HTML was out of the question.
Markdown is a newer markup language that was intended to be easier to read and write. Instead of [i]text[/i], you write
*text*
Learned something new, pedantry FTW!