vs
QUICK ANSWER
"Si" is a form of "si", a conjunction which is often translated as "if". "Por qué" is a form of "por qué", a phrase which is often translated as "why". Learn more about the difference between "si" and "por qué" below.
si(
see
)A conjunction is a word that connects words, phrases, clauses, or sentences (e.g., The cat and the dog slept.).
A masculine noun is used with masculine articles and adjectives (e.g., el hombre guapo, el sol amarillo).
por qué(
pohr
keh
)A phrase is a group of words commonly used together (e.g., once upon a time).
A masculine noun is used with masculine articles and adjectives (e.g., el hombre guapo, el sol amarillo).
