The answer is false.
Although an infinitive phrase shares something in common with a prepositional phrase in the sense that it starts with the preposition "to", they do not have the same function.
Their forms are also different:
While infinitive phrases are made by the preposition "to" and followed by a verb in infinitive form, prepositional phrases are made of any preposition and followed by a noun or a pronoun.
Prepositional phrases indicate places, times, reasons, etc. and can be placed at the end of the sentence or at the beginning followed by a comma. Infinitive phrases can also be placed at the beginning of a sentence followed by a comma and at the end, but it can also be placed in the middle and it always expresses a purpose or a reason.
Prepositions have a broader meaning, as they can talk about time periods, places and agents.
