Gritar vs. chillar
In the Spanish language, there are various words that can be used to describe the act of screaming or shrieking, and two of them are 'gritar' and 'chillar'. While these terms are often used interchangeably, they each have nuanced meanings which may depend on region or personal preference.
Gritar
Generally used to refer to a strong, usually loud utterance that is intentional and often relates to showing or expressing strong emotions such as anger, fear or excitement.
Ella empezó a gritar cuando vio la araña.
(She started to scream when she saw the spider.)
Por favor, no grites, te puedo oír perfectamente.
(Please don't shout, I can hear you perfectly.)
El público gritaba de emoción durante el concierto.
(The audience was screaming with excitement during the concert.)
Chillar
More akin to shriek or squeal. It often refers to high-pitched screams and may hold negative connotations. It may not necessarily express understandable words but instead convey fear, surprise or pain in an abrupt manner.
Los cerdos chillan cuando tienen miedo.
(Pigs squeal when they're scared.)
No necesitas chillar, puedo escucharte.
(You don't need to screech; I can hear you.)
Chilló de sorpresa cuando le dimos la noticia.
(She shrieked with surprise when we gave her the news.)
Summary
'Gritar' represents a general term for screams that express emotions and are understandable. It doesn't always refer to a high-pitched sound. 'Chillar' is used specifically for high-pitched, abrupt screams which may be associated more with shock, fear, or distress than with clear communication through words.