iPhoto Events vs. My Albums

What is the difference between my iPhoto Events (which were how I had organized my photos back in the day, using iPhoto), and what is now My Albums?

Here's what I have done, and understand thus far:

I used to group my photos by month, every year, or the odd time by an event/other criteria (trip to..., etc.). It appears I haven't organized ANY photos for almost 6 years now (WTH?!?).

I watched a great video on how to organize your photos on a mac, but it asks me to delete all past albums and start from scratch (david's tricks to organize your photos - 2019).

I also read in another community discussion thread that deleting photos in events will delete them from the library as well.

SOooo.... What do I do with my old iPhoto events??? - I would rather not have to redo the sorting and labelling of these groups of photos. There are 10 years worth of photos in there, with approximately 12-18 per year.

But I understand that each of those photos in an event is essentially duplicated on my computer, taking up twice the space it needs to. Albums does not do that. So I SHOULD have them in albums, right?

*Is there no way around the re-organizing of these photos?

***Can I create a new album by year, with folders by month, and then drag-and-drop or copy-and-paste the pictures from the 'old' events to the new folders/albums? And then delete the events? Or will there be some problems with doing that?

I better ask for clarification on this too: what is the difference between and album and a folder?

Thanks SO much,

Carla in Canada