Final answer:
REM sleep and NREM sleep are two distinct stages of sleep with different characteristics and functions. REM sleep resembles wakefulness in terms of brain wave patterns and is associated with dreaming. NREM sleep includes three stages with slower brain wave patterns and less frequent dreaming.
Step-by-step explanation:
REM sleep and NREM sleep are two distinct stages of sleep that have different characteristics and functions. During REM sleep, which stands for rapid eye movement, brain waves resemble those observed during wakefulness. This is the stage of sleep where dreaming occurs. In contrast, NREM sleep is subdivided into three stages, each with characteristic patterns of brain waves. These stages are characterized by a decrease in brain wave frequency and an increase in amplitude. Unlike REM sleep, dreaming is less common during NREM sleep.