Although people with little understanding of the two words might think they are the same, there are a lot of differences between the two. However, both are experiences you should never have, especially if you are not having the normal length of sleep. A night terror is usually described as a sleeping disorder that causes someone to have interrupted sleep due to anxiety, panic, and screaming.
A sufferer can experience this when he or she is in a deep state of sleep, and it can also be experienced when you're fully awake. On the other hand, the nightmare is an experience you have when you are asleep with terrifying images of strange things like demons, monsters coming in your dreams.
This can also cause you to be sleep talking. A night terror is usually experienced by younger ones and can only be experienced by adults in rare cases, while nightmares can be experienced by anybody.