| A | B |
| to indicate destination or purpose | para |
| through, by and along | por |
| in behalf of | por |
| in favor of | por |
| instead of | por |
| used after the verbs ir, mandar, volver and venir to show the reason for the errand | por |
| to indicate a time deadline | para |
| to define a period of time | por |
| to express an indefinite time | por |
| when followed by an infinitive, expresses purpose and means "in order to" | para |
| when followed by an infinitive, expresses what remains to be done | por |
| to be about to or to be ready to | estar para |
| to be inclined to | por |
| to express a comparison | para |
| to express means, manner or motive | por |
| in exchange for | por |
| to express an opinion or estimation | por |
| to indicate measure or number | por |