Portuguese is orthographically similar in many ways to Spanish, but it has a very distinctive phonology. A speaker of one of these languages may require some practice to effectively understand a speaker of the other (although generally it is easier for a Portuguese native speaker to understand Spanish than the other way around). Compare, for example:
Ela fecha sempre a janela antes de jantar. (Portuguese)
Ella cierra siempre la ventana antes de cenar. (Spanish)
Some less common phrasings and word choices have closer cognates in Spanish because Portuguese has managed to retain a much larger vocabulary, with stronger Latin heritage:
Ela cerra sempre a janela antes de cear. (less common Portuguese)
(Which translates as "She always closes the window before having dinner.")
In some places, Spanish and Portuguese are spoken almost interchangeably. Portuguese speakers are generally able to read Spanish, and Spanish speakers are generally able to read Portuguese, even if they cannot understand the spoken language.
Portuguese also has significant similarities with Mirandese, Catalan, Italian, French and with other Romance languages. Phonetically, Portuguese sometimes appears closer to French and Catalan than Spanish does. The sound set of Portuguese is very similar to the French one, due to the occurrence of nasalization and some palatalization in both languages, and due to certain sound changes (for example, diphthongization of low-mid stressed vowels, aspiration of /f/, devoicing of sibilants, and change of intervocalic [?] to [?]) that set off Spanish from the others. In lexicon, Portuguese bom (masculine word for good) and French or Catalan bon are very similar, while Spanish bueno is somewhat different, and Portuguese filha, French fille and Catalan filla are opposed to Spanish hija. European Portuguese came under additional French influence as a result of the Napoleonic dominion in Lisbon from 1807-1812, and cultural influences after that.
Speakers of other Romance languages may find a peculiarity in the conjugating of certain apparently infinitive verbs and of some real infinitives. When constructing a future tense or conditional tense clause involving an indirect object pronoun, the pronoun can be placed between the verb stem and the verb ending. This phenomenon is called mesoclisis, because the clitic is neither before nor after, but in the middle. For example, Dupondt said trazer-vos-emos o vosso ceptro. Translating as literally as possible, this is "bring (stem)-to you (formal)-we (future) the your scepter". In English we would say, "We will bring you your scepter." The form Nós vos traremos o vosso ceptro. is a regionalism used in most Portuguese speaking countries, as well as Portugal.