You might like the explanation here: https://georgesenglish.com/misc/sovery.html

Hi dear Mary

It depends on the context, but "so" is usually stronger than "very." For instance, if you really like the cake, better to say "the cake is so good" rather than "the cake is very good."

They're the same if you mean 'much' by them. But there are a lot of different meanings for "so"

So is used as an adverb. Very can be an adverb and an adjective! They are both very similar though so I wouldn’t fret