I was led astray because the voice was the lady's voice lol... so my mind reversed the words unconsciously, and didn't catch the error until I was marked wrong. Haha, gotta pay attention I suppose, because sometimes you just don't know.
Both mean "you are" and are counted as correct here on Duolingo.
In real life, use "vous" with groups of people (plural you) and to address strangers, your boss, your teacher, and anyone to whom you owe respect (singular you).
Use "tu" for family, friends, and children.