Yes, a tariff is a tax. But not all taxes are tariffs. The words are not synonyms.
As for the rest of your rant, it's odd how little tariffs are mentioned by the south as the motive for secession, and how often slavery is mentioned.
Spare me. Their constitution TOTALLY FORBADE imposing tariffs for "internal improvements" (a direct reference to Lincoln's American System) with the exception of making waterways and even then that was very, very limited.
Bear in mind that the govt's primary source of revenue then was tariffs, not income taxes as it is today. They literally said "No tariffs for federal improvements"
Sure, they said slavery should be legal, but so did one out of five of the Northern states (really more, because the north counted as allies western territories that had nothing to do with the issue. In fact, the large Indian tribes fought IN SUPPORT of the south).
But the Confederacy actually FORBADE international slave trading, following the then-liberal ideas of the day.
Geeze...