What is the difference between cascada and catarata as translations for the English "waterfall"? Are they synonyms, or is there a difference?
In some way are synonyms, but
catarata is used for big waterfalls. Of course, this is a subjective difference. For a waterfall in a little creek you say
cascada for sure, but not
catarata. And, for example, the translation of:
Niagara Falls → Cataratas del Niágara
¿Son las cataratas del Niágara cascadas? Sí.
Catarata refers to a large, rushing MASS of falling water. Cascada refers to a more gentle falling of water, usually broken up into smaller units called "waterfalls."
What passes for a waterfall can be classified into many different subtypes, not just casacadas y cataradas.
One doesn’t usually think of a “rapid” as one, but in a way it is. Indeed, Wikipedia mentions that:
Una rápida es una característica hidrológica entre una corrida (una parte fluida de un arroyo) y una cascada.
Don’t confuse corridas de agua with corridas de toros, though. :)
Cascada is the prefered form in Spain, and
catarata, the one in Latin America.