It seems as though Zettelkasten, despite being a relatively old phenomenon (e.g. see Niklas Luhmann), is experiencing a renaissance these days. Ultimately, it is just (yet) another way of keeping track of your notes and thoughts. You can think of it as cataloguing everything you write down. I reckon whether you stand to gain anything from converting your existing note-taking to a Zettelkasten operation depends entirely on how you currently take notes. What really matters is that whatever approach you employ works for you. In general, I wager the mere act of actually writing something down and approaching material in a critical, thoughtful manner as opposed to merely consuming is what drives both retention and understanding. Zettelkasten might help you attain that. It might also not.
The difference lies in how it's organized. An encyclopedia such as Wikipedia is organized using an encyclopedic hierarchy of knowledge. That makes no sense for a personal linked notes system: the key is to avoid hierarchy, and tag and link the notes in a way that helps them surface on the contexts you need.
I'd describe it as a certain style of private wiki. It comes with certain conventions how a wiki page should be. The article describes it as atomic, self-contained, permanent, and concise.
