[dalmo3]

The tiddlywiki site is a tiddlywiki document. That alone tells you the difference.

[scubbo]

That one is optimized to be a web site and the other is optimized to be a personal note-taking platform? ;P

[kvark]

A markdown document (e.g. from Obsidian) can be hosted as easily.

[karencarits]

Yes, but the tiddlywiki file is the entire wiki. You've perhaps tried the dataview plugin for obsidian? Tiddlywiki is built on a similar idea, but much more flexible and powerful. However, tiddlywiki doesn't support in-text definition of fields (as far as I know)