Both Tú and Usted literally mean you, but there is a significative difference between them.

It can be confussing since in English we don't have an informal way and a formal way of referring to someone using "you".

FORMAL VS INFORMAL

Usted is a more respectful way of talking to someone, such as a new acquaintance, an older person, or someone you consider to be of higher rank or anyone to whom you wish to show respect. Use Usted with authority figures and most strangers.

Tú is less formal than usted. It demonstrates a certain closeness and informality. Use tú in a casual conversation, with someone from your same age, or in a relaxed environment.
To refer to children, family, close friends use of tú is recommended.

Use of Tú and Usted changes from region to region within each country.

You should use usted to addres:

- Strangers.
- People whom you wish to show respect.
- An older person who you want to show respect (for example your friend's grandfather)
- An honorable figure or an authority.
- A public audience (using ustedes)

You should use tú to addres:

- Friends
- Children
- Classmates
- Family
- Pets
- In general anyone who addresses to you using you.


ME PUEDES TUTEAR

If you are not sure you can always start with usted and if you feel confortable switch to tú. If the person who you are talking to replies, "tutéame por favor" or "me puedes tutear", means you can go ahead and use tú!

*Tutear = to address using the familiar tú form

Let me know if you have questions or specific examples.

"Allá donde fueres haz lo que vieres"
"Wherever you're going do whatever what you're seeing"