Why is the Texas Revolution called a revolution when it was more of a civil war? Texas at the time was a state of Mexico and the people in Texas had different opinions on issues such as slavery and government, much like the American Civil War. It was not the overthrow of government it was a war between citizens of the same country so shouldn't it be considered a civil war and not a revolution?
I think it's reasonable to argue that calling it the "Texas Revolution" makes sense given the history of the region. By the time hostilities erupted the vast majority of the population were American settlers, white and black. They outnumbered the Tejanos population several times over. While many of the Tejanos, if memory serves, did side with white Texans, the conflict was in large part a conflict between the Mexican government and foreign-born inhabitants trying to sever Mexican territory away from the rest of the nation.
Further, I'm uncertain whether they were citizens in the unproblematic way the OP suggests (but I might be wrong on this so feel free to correct me). Yes, American settlers had been invited into Texas by the government but prior to actual hostilities Santa Anna had tried to revoke the original land grants given to Moses/Stephen Austin. Did this still make them citizens? Had they ever been full Mexican citizens? Did their practice of slavery in defiance of Mexican law complicate this?
As for overthrow of government, revolutions by no means need to try and destroy the original government completely. They can just seek to overthrow its control over a specific area. The American Revolution didn't try to destroy the British Crown, nor the many Latin American revolutions of the 1820s (including Mexico's Independence) try to overthrow the Spanish monarchy, nor did all the European Revolutions of 1848 seek to completely destroy existing governments (some certainly did, but I'm thinking of, for example, Hungary trying to break off from the Austrian Empire).
Only failed revolutions are called civil wars. If the rebels win, it was a revolution. later, there was a 10 year Mexican civil war from 1910-1920. The rebels won and the winners call it the Mexican revolution.