Both can mean 'darse cuenta', but one implies mental understanding and the other sensory perception.
Verb. To come to understand or become aware of something you did not know or had not thought about before.
I just realized I left my keys at home.
Acabo de darme cuenta de que dejé mis llaves en casa.
She realized she was in love with him.
Ella se dio cuenta de que estaba enamorada de él.
Did you realize how serious this is?
¿Te diste cuenta de qué tan grave es esto?
Verb. To perceive or detect something with your senses or attention. The perception comes from something external.
Did you notice anything strange in the room?
¿Notaste algo extraño en la habitación?
She noticed that he was wearing a new tie.
Ella notó que él llevaba una corbata nueva.
I did not notice the sign.
No noté el letrero.
Common mistake
Using "realize" when the act is sensory perception. Wrong: "I realized a strange smell." (correct: I noticed a strange smell.)
Trick to remember it
"Realize" = mental understanding (something clicks in your mind). "Notice" = sensory perception or attention (you see it, hear it, smell it). Is the "darse cuenta" mental or sensory?
Quick rule
Does the understanding come from your mind (connecting ideas)? Use "realize". Does the perception come from your senses (seeing, hearing, smelling)? Use "notice".
Did you know?
Note: American English spells it "realize"; British English spells it "realise". Both are correct. "Realize" also has a secondary meaning: "to realize a profit" (to generate a gain) or "to realize a dream" (to make a dream come true). This use is unrelated to "darse cuenta".
Exercise 1 · Pick the right one
I just _____ that I left the oven on!
Exercise 2 · Pick the right one
Did you _____ the new painting on the wall?
Exercise 3 · Form the word
Does the understanding come from your mind (connecting ideas)? Use "realize". Does the perception come from your senses (seeing, hearing, smelling)? Use "notice".
Using "realize" when the act is sensory perception. Wrong: "I realized a strange smell." (correct: I noticed a strange smell.)
"Realize" = mental understanding (something clicks in your mind). "Notice" = sensory perception or attention (you see it, hear it, smell it). Is the "darse cuenta" mental or sensory?
Bryan López
Founder of SpeakUP Academy