Nightmares differ from night terrors though. To quote Wikipedia:
Night terrors are distinct from nightmares.[31] In fact, in nightmares there are almost never vocalization or agitation, and if there are any, they are less strong in comparison to night terrors.[31] In addition, nightmares appear ordinarily during REM sleep in contrast to night terrors, which occur in NREM sleep.[2] Finally, individuals with nightmares can wake up completely and easily and have clear and detailed memories of their dreams.[2][31]
Night terrors are distinct from nightmares.[31] In fact, in nightmares there are almost never vocalization or agitation, and if there are any, they are less strong in comparison to night terrors.[31] In addition, nightmares appear ordinarily during REM sleep in contrast to night terrors, which occur in NREM sleep.[2] Finally, individuals with nightmares can wake up completely and easily and have clear and detailed memories of their dreams.[2][31]
https://en.wikipedia.org/wiki/Night_terror
For a good description of what they are like, read the "Signs and Symptoms" section of that article (https://en.wikipedia.org/wiki/Night_terror#Signs_and_symptom...).