História vs. conto
In Portuguese, the words história and conto can both relate to the idea of a story, but they are not interchangeable. História is a very broad and common term covering various types of narratives, while conto is a much more specific term, primarily used in a literary context.
História
A2The word história has two main meanings. First, it means history, referring to the study of the past or the actual events that occurred. Second, it is a broad term for any story or narrative. This can be a personal account of events, a novel's plot, a movie's storyline, a rumor, or an excuse.
Eu adoro estudar a história do Egito Antigo.
(I love studying the history of Ancient Egypt.)
Ele me contou a história da vida dele.
(He told me his life story.)
Qual é a história desse filme que você está assistindo?
(What is the story of that movie you are watching?)
Todo dia ela chega atrasada com uma história diferente.
(Every day she arrives late with a different story.)
Vou contar uma história para as crianças dormirem.
(I'm going to tell a story for the children to fall asleep.)
Conto
B1The word conto refers specifically to a short story as a literary genre. It is a concise, fictional piece of prose. It is not used for real events or long narratives like novels. A very common fixed expression is conto de fadas, which means fairy tale.
Machado de Assis é famoso por seus romances e contos.
(Machado de Assis is famous for his novels and short stories.)
Li um conto de ficção científica muito interessante ontem.
(I read a very interesting science fiction short story yesterday.)
Cinderela é o meu conto de fadas preferido.
(Cinderella is my favorite fairy tale.)
O prêmio literário foi para um livro de contos.
(The literary prize went to a book of short stories.)
A professora pediu que escrevêssemos um conto de terror.
(The teacher asked us to write a horror short story.)
Summary
The key difference is scope. História is a general term for any story or narrative, real or fictional, and it also means history. Conto is a specific term for a literary short story. Therefore, every conto is a type of história, but most histórias are not contos. If you are talking about a specific literary form (a short story), use conto. For everything else, from a personal anecdote to the plot of a saga, história is the correct word.