Final answer:
The underlined words in the sentences are both infinitive phrases, but they have different functions.
Step-by-step explanation:
The underlined words in the sentences are both infinitive phrases, but they have different functions. In sentence a, "to give her sister a gift" acts as the direct object of the verb "wanted." In sentence b, "to the mall" functions as an adverbial phrase, providing information about when Tori went to the mall.