Complex sentence: Writers including Lewis Spence define kelpies as spirits living beside rivers, whereas water horses live beside lochs, a distinction not universally applied, as others ascribe the term "kelpie" to a wide variety of mythical creatures.
Split into simpler sentences: Writers including Lewis Spence define kelpies as spirits living beside rivers, whereas water horses live beside lochs. Others do not universally apply this distinction, using the term "kelpie" to describe a wide variety of mythical creatures.