I don’t think there is any difference, just offering it on multiple platforms. I even had Galdor’s Grip on PnPArcade at one point but was iterating too much during development last year that I had to keep asking them to update files and images whereas itch.io gives me full control of uploads and page design.
I hadn’t really pursued a publisher for this game because I had planned to make expansions and improvements first. However, I lost the original card files and design notes and became disheartened. I really do need to re-examine this design this year and expand/improve upon it.