www.wysiwygwebbuilder.com

Is the last year's version different from the new version, I mean the plus version additions. I have a dilemma when updating, are the add-ons the same? I would not like to buy a set of add-ons that I have already purchased

You can download the demo, and it has an improvement and change document inside that tells you all the changes (there are over 150 changes) along with bug fixes. All the extensions work with the new version.

There is also a thread in the forum that also tells you the changes.

Sure, because you support great stuff

Is the last year's version different from the new version, I mean the plus version additions.

This year's plus version has 3 new extension packs:
https://www.wysiwygwebbuilder.com/audiopack1.html
https://www.wysiwygwebbuilder.com/navigationpack5.html
https://www.wysiwygwebbuilder.com/gallerypack2.html