I use Obsidian alot, they are very different in how they work as far as I can tell. Obsidian is more like a pure notebook with a HUGE amount of useful plugins. I use the KanBan and OCR functions alot with their Google-esq search.

I’m told they’re similar, but I’ve never used Obsidian.

Logseq vs Obsidian - which PKM tool should you use?

Logseq is a block-based outliner, allowing you to organise information into a tree-like structure using bullet-points. You can think of it as a mind-map, but for text. This allows users to quickly structure and add hierarchy to their information by indenting information, and to also move quickly between different branches of information.

[…]

In contrast to the outliner approach, Obsidian is a page-based application that functions like a long-form text editor, similar to a Microsoft Word document. The key advantage over traditional word processors is the instant searchability of all files and folders, as well as seamless linking between different pieces of information.

How to use Obsidian and Logseq together and why Markdown matters