Debounce is like hitting the snooze button on your alarm clock. You are trying to wake up, but you’re just not there yet. Debounce is you saying not yet, not yet, not yet—and this could go on forever. Theoretically you might never wake up. A real world example might be preventing a chart from being redrawn while the window is resized by some maniac who has nothing better to do than expand and shrink his browser incessantly for five minutes. Only when the activity stops for, say, two seconds will the chart be redrawn.
With throttling, on the other hand, something will happen every so often. Let’s say the maniac above decides to click a button that reloads the chart over and over again putting a strain on your backend. With throttle, the data would be fetched from the backend, but only every ten seconds.