That's definitely not true. While fonts may be the same, colours are definitely not. Many terminals support a very large array of colours. Lots of tools have animations for progress bar, and a shell us no guarantee of being responsive. Anything that displays git statuses in the prompt will take multiple seconds to be ready on a large project, and many will just silently pause while they chug away at whatever they're doing.
In terms of responsiveness, there are plenty of terminal based apps that respond poorly to window resizing (the flickerkng is incredibly frustrating to me), or just don't handle aspect ratio changes at all and clip the ends of lines. Some tui applications don't clear their screen buffer properly on quit so completely break scrolling back the terminal. Many terminals really suck for performance and can really really chug if you accidentally dump a large JSON file to the terminal, for example. That's not responsive at all.
