What is the difference between rem behavior disorder and somnambulism (sleep walking)?

Sleepwalking is a sleep disorder characterized by walking or other activity while seemingly still asleep, REM sleep behavior disorder (RBD) is a parasomnia. A parasomnia involves undesired events that happen ... RBD can be confused with sleepwalking and sleep terrors. In these other disorders, the sleeper is usually ... RBD episodes occur during rapid-eye-movement (REM) sleep. Normal sleep consists of a series of REM ...

The whale was a missile blasting from beneath the surface.  2.) a majestic whale leapt skyward before diving back into the sea.    these are both figurative language. this is so because the whale in sentence "1" was not actually a missile, nor was it actually blasting. now, for sentence "2", a whale can not actually "leap".