There is that old and reliable indicator of when a politician is lying: his mouth is open. There is, however, an exception to this rule: when he’s talking about raising taxes. Then you can trust his announcements.
For this reason, it is no surprise that the word “tariff” derives from an old Arabic root meaning “announcement.” It was assumed that any government “announcement” was going to cost you something. Eventually, the word referred to officially-published lists of customs duties throughout the shipping world. A tariff traditionally, then, is a tax on imports or exports. In the U.S., tariffs can only be levied constitutionally on imports.
Tax” is more general. It comes from the Latin word taxare which means “to handle,” in the sense of “examine personally for the purpose of assessment”—a euphemism for “invade one’s privacy.” Taxare is likely a form of the Latin tangere which means “to touch,” as in “touch what ain’t yours.” Thus, the taxman first invades one’s privacy, then takes their property. The taxman’s “touch” should be considered equivalent to a TSA “enhanced patdown.” The latter has his hand squarely in your crotch, the other in your pocket. One takes your dignity, the other your substance. It’s government as usual.