The immense difference is that all the states entered voluntarily into the Perpetual Union. The attempt to destroy that was treasonous, and was justly put down.
The "perpetual union" didn't exist after the Constitution was approved. The Articles of Confederation were thrown into the waste bin. Furthermore, the idea that you can't leave a club you have joined isn't supported by any theory of law. Only bootlicking statists make such claims.
I have seen theories like yours proposed hundreds of times in this forum. They are not just wrong, they are absurd. There is no theory of law that supports them. Not national law, nor international law.
You believe in a fantasy. You're a fool.