vs
QUICK ANSWER
"Si" is a form of "si", a conjunction which is often translated as "if". "Lo vi" is a phrase which is often translated as "I saw him". Learn more about the difference between "lo vi" and "si" below.
lo vi(
loh
bee
)A phrase is a group of words commonly used together (e.g., once upon a time).
a. I saw him
Ayer llegó mi hermano. - ¡Sí! Lo vi en la biblioteca.My brother arrived yesterday. - I know! I saw him in the library.
b. I saw it
¿Sabes por casualidad dónde está mi teléfono? - Lo vi sobre la mesa.Do you happen to know where my phone is? - I saw it on the table.
c. I saw you
Anoche lo vi caminando por la calle, pero usted no me vio.I saw you walking along the street last night, but you didn't notice me.
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).
