QUICK ANSWER
"Ser" is a copular verb which is often translated as "to be", and "estar ocupado" is an intransitive verb phrase which is often translated as "to be busy". Learn more about the difference between "ser" and "estar ocupado" below.
ser(
sehr
)A copular verb links the subject of a clause to the predicate (e.g., My brother is tall).
An intransitive verb is one that does not require a direct object (e.g., The man sneezed.).
a. to be made of
El casillero antiguo de mi abuela es de roble.My grandma's antique dresser is made of oak.
a. to root for
Yo soy del mejor equipo del mundo: FC Barcelona.I root for the best team in the world: FC Barcelona.
An impersonal verb is a verb with no apparent subject (e.g., Llueve en España.).
a. to be
Son las siete de la mañana.It is seven in the morning.
Era de noche cuando llegaron.It was night when they arrived.
An auxiliary verb, or helper verb, is a conjugated verb that comes before a main verb and determines the main verb's tense, mood, or aspect (e.g., I have gone.).
a. to be
El edificio fue diseñado por un equipo de arquitectos.The building was built by a team of architects.
A masculine noun is used with masculine articles and adjectives (e.g., el hombre guapo, el sol amarillo).
estar ocupado(
ehs
-
tahr
oh
-
koo
-
pah
-
doh
)An intransitive verb phrase is a phrase that combines a verb with a preposition or other particle and does not require a direct object (e.g., Everybody please stand up.).
a. to be busy
No puedo salir a jugar ahora. Estoy ocupado.I can't go out to play right now. I'm busy.
a. to be taken
Este asiento está ocupado. El hombre que está aquí simplemente fue al baño.This seat is taken. The man that's sitting here just went to the bathroom.
b. to be occupied
El baño estaba ocupado, por lo que fui al que está en el tercer piso.The bathroom was occupied, so I went to the one on the third floor.
c. to be busy (telephone)
El número está ocupado. Llamaré de nuevo en diez minutos.The number is busy. I'll call again in ten minutes.
