QUICK ANSWER
"Hablar de" is an intransitive verb phrase which is often translated as "to talk about", and "notar" is a transitive verb which is often translated as "to notice". Learn more about the difference between "hablar de" and "notar" below.
hablar de(
ah
-
blahr
deh
)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.).
1. (general)
a. to talk about
Siempre terminamos enojados cuando hablamos de política.We always end up upset when we talk about politics.
b. to speak about
La testigo está en estado de shock y todavía no puede hablar de lo que vio.The witness is in shock and still can't speak about what she saw.
notar(
noh
-
tahr
)A transitive verb is a verb that requires a direct object (e.g., I bought a book.).
a. to notice
Noté que saliste muy temprano de tu casa hoy.I noticed that you left home very early today.
a. to feel
¿No notas nada en el brazo? Tienes un rasguño grande.Don't you feel anything on your arm? You have a big scratch.
a. to mark
Después de platicar con el abogado, revisé el documento y noté las páginas importantes.After talking with the lawyer, I reviewed the document and marked the important pages.
b. to indicate
Permíteme notar cuál es la sección que debes estudiar.Allow me to indicate which section you should study.
An impersonal verb is a verb with no apparent subject (e.g., Llueve en España.).
a. to be noticeable
¿Se nota que mis patillas están disparejas? - No, para nada.Is it noticeable that my sideburns are uneven? - No, not at all.
notarse
A reflexive verb is a verb that indicates that the subject performs an action on itself (e.g., Miguel se lava.).
a. to feel
Me noto más alerta en la mañana que por la noche.I feel more alert in the morning than at night.