An infinitive phrase has much the same form as a prepositional phrase beginning with the preposition to and serves much the same function.
An infinitive phrase has much the same form as a prepositional phrase
beginning with the preposition to and serves much the same function is false. A
prepositional phrase will begin with a preposition and ends with a noun,
pronoun, gerund or clause whereas the infinitive phrase begins with the
infinitive (to).