Come si dice in Portoghese (Brasile)? Como dizer "Sign in" e "log in" em português do Brasil?
E existe alguma diferença entre essas frases?

Vedi una traduzione

"Sign in" and "log in" are often used interchangeably as synonyms, especially in modern digital contexts. While there might be a subtle difference between the two terms, it's common for websites, apps, and software to use either term to refer to the process of accessing an account that requires authentication. In fact, some websites use both terms on the same page or interface to cater to users who may be more familiar with one term over the other. Ultimately, whether you use "sign in" or "log in", the process is the same: you enter your credentials to access an account or system.

You could use the following labels in Portuguese to convey the same idea:
-- “Entrar”
-- “Fazer login”