vs
QUICK ANSWER
"What" is a form of "what", a pronoun which is often translated as "qué". "When" is an adverb which is often translated as "cuándo". Learn more about the difference between "what" and "when" below.
what()
A pronoun is a word that stands in for a noun (e.g., she).
An adjective is a word that describes a noun (e.g., the big dog).
An interjection is a short utterance that expresses emotion, hesitation, or protest (e.g., Wow!).
when()
An adverb is a word that describes a verb, an adjective, or other adverbs (e.g., to run quickly, very tired).
A conjunction is a word that connects words, phrases, clauses, or sentences (e.g., The cat and the dog slept.).
2. (relative)
