Afghanistan is a landlocked country on the other side of the planet, the soldiers didn't grow up with knowledge of the terrain, they had no knowledge of the language, culture, customs or social networks, no one locally (with few exceptions) wanted them there, and crucially they only lost once they left, and when they left, there were no penalties for the people who started the war; no US politicians were in any danger whether the war was won or lost, no land was lost, and no truly important geopolitical goals failed.

On the flip side in any domestic insurrection, the soldiers know the terrain, language, customs and culture of the people, the supply lines are nothing (rather than having to airlift materiel and people thousands of miles, you drive them on regular roads), the infrastructure supports espionage, most people support the regime and will collaborate to return to stability (since they voted for it), the regime never leaves (you can leave Afghanistan, you can't leave your own country or it ceases to be a country), and if you lose, you lose territory and/or politicians run the risk of violence. The stakes are why these comparisons are never relevant.