tú (with accent mark)
This is a subject pronoun and refers to the subject of the sentence. It corresponds to the English “you” (second person, singular fam). In most cases, the subject pronoun is optional in Spanish and usually not used.
(Tú) eres muy inteligente – You are very intelligent.
tu (without accent mark)
This is a possessive adjective and is used to demonstrate possession, ownership or relationship of a noun. It corresponds to the English possessive adjective, “your.”
This is an indirect object pronoun (in the case of your example above, but also shares the same form as direct object pronoun) and is used to name the object of a sentence. In this case:
Te gusta jugar baloncesto – Basketball is pleasing to you (you like basketball).
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This is what is called a disjunctional or prepositional pronoun. That is to say that it is the pronominal form that you will find following a preposition. In your example above, “a ti” is a restatement of the indirect object pronoun, and it is added in order give emphasis or clarity to the statement.