vs
QUICK ANSWER
"Who" is a form of "who", a pronoun which is often translated as "quién". "When" is an adverb which is often translated as "cuándo". Learn more about the difference between "when" and "who" below.
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)
who()
A pronoun is a word that stands in for a noun (e.g., she).
a. quién
Hello? Who is calling?¿Hola? ¿Quién llama?
I don't know who he is, but he looks a lot like my brother.No sé quién es, pero se parece mucho a mi hermano.
2. (relative)
