BOTH were decided by force.
Yes, but one wasn't supposed to be. We changed the rules, remember? Force shouldn't have been required in the second case, because the principle that people had a right to leave had been won. Our Nation was founded on a new Paradigm, and not that of the British Union.
Had we followed our own paradigm, we would have accepted the same right for others, that we demanded the British accept from us.
You fail to make necessary distinctions.
We separated from Great Britain because King George III and Parliament had become tyrants.
The Confederacy tried to separate from, and declared and launched war upon, the Union, in the name of their claim to a “right” to tyrannize others, and to expand that tyranny into the states that had outlawed such tyranny.
Big difference. Which of course is a major reason for the completely different results obtained.
The American Revolution had a moral basis. The Confederacy had an immoral basis. End of story.
No, we didn't change the rules. President Washington himself put down some rebellions.
The rules have always been the same. There are existing governments. If you want to challenge or overthrow an existing government, expect a fight. You may win, but you may lose.
And, if you'd like, accompany your attempt with a nice letter explaining your reasons. Have a "decent respect" for the opinions of others. The secessionists did all that. The difference is that they lost the subsequent fight.