You’re indeed right! Different copyright year, different HP thickness, Shadowless instead of Shadowed of course, and a lighter overall color are the most notable differences regarding Shadowless vs Shadowed. I noticed the same when I look at my Base Pikachus, and I also mention it in my Base Pikachu artwork variations article (also useful for Base Set variations in general).
And welcome to the forum, @silentoaths! The three first gen starter final evolutions always look great, no matter how many times I’ve seen them! Great artworks, great cards in general, great collector pieces; not to forget that it all started with these artworks in 1996 (Japanese No Rarity release).
Good luck with your graded collection!
Greetz,
Quuador