Did vital have no updates whatsoever after release 3 years ago, or are the updates not open source?

There are some threads on the forum, but no answer to the question of whether any new code will appear.

https://forum.vital.audio/search?q=source

So what would be the difference between the two of them?

Vital is a wavetable synth, Helm a "traditional" subtractive synth.

There's a good course on skillshare/udemy that teaches synthesis and sound design using Vital

https://www.udemy.com/course/the-complete-beginners-guide-to...

Vital is effectively NOT open-source, the source available on github is a single snapshot of the source as it was when 1.0 was released, it has not been updated since, and 1.5.5 is vastly different.