ITunes Vs. Music file storage - what can I get rid of?

I have a huge amount of Music on file, beginning with iTunes and going back more than 20 years. I am starting to understand that "Music" (not the Apple subscription service, but the replacement for iTunes) functions a bit differently in terms of file storage.

I am loathe to get an Apple Music subscription, primarily because I hate to put all the music that I purchased, either through downloads or from ripping from CDs at risk for loss, even if only due to commonly mentioned screw-ups with cover art replacement.

As well, I frequently use transcription software to study jazz, which is not amenable to download service based music like Spotify, Pandora and presumably Apple Music services.

However, I am coming to vaguely understand that I have a mostly duplicated set of tunes in my vast library (over 40,000 items in total, although that may be double the actual figure – keep reading) and I am looking to downsize in order to relieve some of the mounting pressure on hard drive storage.

As I understand it, somehow in the "upgrade" to Music from iTunes (or perhaps under the "Organize Library" menu command) Music duplicates and consolidates all of the music files it can find into a new location, without deleting the earlier library source material.

The challenge for me is in identifying the files that I can safely throw away. I have an idea, but want to be sure, before I take the chance of offloading what I think I can delete onto an external drive, then deleting those tunes, only to find that that somehow disrupts my library.

Under my sidebar menu, there is both a folder for Music and for iTunes (which I probably put there in years past) , as well as an iTunes folder nested within Music.

Both Music and iTunes have a Media folder which then contains the actual "Music" folder where all of my tunes/recordings are nested. (wow, great labelling strategy, Apple.)

These folders are nearly duplicates of each other, with the one that does NOT contain an Album Artwork folder a few GB larger. I have come to understand that "Music" incorporates the album artwork, thereby obviating the need for a separate folder for storage.

Given the larger size and number of tunes in the "Music" folder, as well as the presence of the Album Artwork folder in the iTunes folder, I'm assuming that the entire iTunes folder can be trashed safely (although thereare still folders with Home Videos and Movies present.... Another matter that I'm not sure what to do with just yet.)

So, can anyone tell me which Media>Music folder contents I can safely trash, while maintaining my music library intact? I'm going to assume it's the iTunes>Media>Music contents that could go.

FYI, the folder sizes are 413 GB for the Music>Media?Music folder and 381 GB for the iTunes>Media> Music folder, which makes sense if newer downloads have been directed towards the first pathway.

You can see why I would like to get rid of 381 unnecessary GB of data, if possible, but there is no clear path or discussion on this in any help files I can find.

Thanks to anyone who has the answer!