It is generally designed as an alternative to headphones connected to portable media players.
A speaker pillow is intended to improve sleep as it is more comfortable than other options for sound.
[1] Example uses include playing audiobooks, podcasts, or music to help fall asleep.
The other type has a small, flat speaker in the center of the pillow, which can be plugged into an audio device using a headphone jack.
However, this type of speaker pillow is known to break very easily.