vs
QUICK ANSWER
"Si" is a form of "si", a conjunction which is often translated as "if". "Porque" is a form of "porque", a conjunction which is often translated as "because". Learn more about the difference between "si" and "porque" 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).
porque(
pohr
-
keh
)A conjunction is a word that connects words, phrases, clauses, or sentences (e.g., The cat and the dog slept.).
a. because
Mi hermano está triste porque no ganó el concurso.My brother is upset because he did not win the contest.