Tu is written without an accent on the u. It is a possessive adjective. The direct English translation is your (singular informal).

Whats the difference between TU and tú?

Tú is a subject pronoun, you informal, the familiar usage as opposed to usted, (sing/ formal.) Tu is a possessive adjective, your, informal, su your (formal). Hope this helps.

Is Tu in Spanish formal or informal?

There are two ways of saying "you" in Spanish: usted and tú. Many Spanish teachers will tell you that usted is used in formal situations, while tú is informal.