For example, what’s the difference between these two signs: the text or the typography?
Is typography an art? That’s like asking if photography is an art. Certainly there are photographers and typographers whose ideas and techniques raise their work to the level of art. But at their core, both photography and typography perform a utilitarian function. The aesthetic component is separate. Being an effective typographer is more about good skills than good taste.
Don’t infer from the highway-sign example that typography is another word for font. Fonts are part of typography, but typography goes beyond fonts.