UniV

The difference is significant:

Weld:

1. First tries to weld edges — it starts with edges where both sides are selected, and if none are found, it attempts to weld edges where only one side is selected. If there's nothing to weld, it performs a Stitch operation between islands (It turns out to be very convenient.).

2. Weld can also merge vertices based on distance.

Stitch:

1. Cannot merge vertices, it only performs stitching.

2. Has a Stitch Between option — select two islands, and Stitch will be applied at the shared edges.

But that’s not all — these operators are separated because they’ll continue to improve and become more distinct over time.

And by the way, you won’t have to wait long for updates: in the next release, Stitch will get a padding option, and both operators will gain support in the 3D viewport. You can already head over to the Discord links to find the latest Pro version of the addon and ask any questions you have.

A lot of functionality is hidden behind operator options and context. What was requested is actually already available in the Align tools (the arrow icons)—you just need to switch the Element Mode to Face or Island, then Shift-click the Align operator (excluding Horizontal, Vertical, and Center).

In the next release, a dedicated Pie Menu [X] will be added for the Align operator, making it much easier to access and tweak settings.

For feature requests, bug reports, or further discussion, there’s a Discord channel linked in the description.

Thanks for the report, but it's better to send bug reports to github, discord, or mail - Oxicid2019@gmail.com, as you can't reply twice to a message in review.

I suspect this is because the update did not delete the old files, try to open the folder with the addon and manually delete the addon and then reinstall.

I would also like to know what error is displayed in the blender console, what OS you are using and what version of blender.