I'm Sorry
Use for more serious apologies or to express sympathy (like 'I'm sorry to hear that'). It literally means 'I feel it'.
Use as 'excuse me' to get someone's attention or apologize for a minor inconvenience. This is the formal 'usted' version, which is always a safe choice.
Use this to say 'excuse me' when you need to pass by someone. It means 'with permission'.
Sorry, I didn't see your message.
I'm very sorry, your grandmother is sick.
Excuse me, is this the line for the bus?
Oops, sorry! I stepped on you.
Excuse me, I'm going to pass.
The distinction between 'perdón' (for minor mistakes), 'lo siento' (for sympathy/bigger mistakes), and 'disculpe' (to get attention) is standard across the Spanish-speaking world.
You will hear 'Disculpá' instead of 'Disculpa' (the informal 'tú' form). This is because Argentina uses 'vos' instead of 'tú'. The formal 'Disculpe' remains the same.
The usage is the same, but you may hear 'disculpad' when addressing a group of people informally, which corresponds to the 'vosotros' form not used in Latin America.
Usage is standard. 'Perdón' is very common for bumping into someone, 'con permiso' is essential for moving through crowds, and 'lo siento' is reserved for more heartfelt apologies or condolences.
Using 'lo siento' for everything. — English speakers often say 'sorry' for minor things like bumping into someone. In Spanish, 'lo siento' can sound too dramatic for this. Use 'perdón' for small accidents.
Using 'perdón' to express sympathy. — If someone tells you sad news, saying 'perdón' is incorrect. It means you're apologizing for something you did. You must use 'lo siento' to show empathy.
Saying 'Soy siento'. — This is an incorrect direct translation of 'I am sorry'. The correct phrase is 'Lo siento'. The 'lo' means 'it', so you are literally saying 'I feel it', referring to the situation.
Confusing 'perdón' and 'con permiso'. — Use 'con permiso' *before* you need to pass someone. Use 'perdón' *after* you accidentally bump into them.