Disregarding pronunciation differences, Spanish and Portuguese are very similar languages. A large proportion of the vocabulary, including conjugated verbs, of each language can be derived from the other one by simple transformation rules.
However, quite a few often-used words are different. I am compiling a list of them here.
The idea is to include only words with a different etymological meaning here. Some words seem very different at the surface, but the difference can easily be explained by transformation in the course of each language's history.
Next is a list of words that are not included, and the reason why not.
| Spanish word | Portuguese word | Reason for non-inclusion |
| mujer | mulher | Spanish j corresponds regularly to Portuguese lh |
| hijo | filho | Spanish h corresponds regularly to Portuguese f |
| solo | só | Portuguese loss of l between vowels |
| cena | ceia | Portuguese loss of n between vowels |
| tener | ter | Portuguese loss of n between vowels |
| solano | soão | Portuguese loss of l between vowels; n between a and o gets lost but nasalises the diphthong |
| playa | praia | Latin pl regularly developed into pr in Portuguese |
| llorar | chorar | Latin pl regularly developed into ll in Spanish, and into ch in Portuguese |
So here are the words that are included:
| Spanish word | Portuguese word | English meaning |
| todavía, aún | ainda | still, yet |
| pueblo, aldea | aldeia | village |
| pueblo | povo | people |
| romero | alecrim | rosemary |
| aduana | alfândega | customs (at port of entry) |
| desayuno | pequeno almoço | breakfast |
| balsa | jangada, balsa | raft |
| columpio, mecedor | baloiço, balouço | swing (Italian: altalena) |
| olvidar | esquecer | to forget |
| coche | carro | car |
| olor | cheiro, odor | smell |
| tren | comboio | train |
| bailar | dançar | to dance |
| baile | dança | dance |
| Spanish word | Portuguese word | English meaning |
| donde | onde | where |
| dedonde | donde | from where |
| menú | ementa | menu |
| mientras | enquanto | while |
| cuchillo | faca | knife |
| cerrar | fechar, cerrar | close |
| quedar | ficar | to stay, to remain |
| caer | cair | to fall |
| caída | queda | fall (the act of falling) |
| pollo | frango | chicken |
| botella | garrafa, botelha | bottle |
| Spanish word | Portuguese word | English meaning |
| amar | amar | to love |
| querer | querer | to want |
| querer | gostar de | to love |
| gustar | gostar de | to love, to like; different usage 1 5 |
| guitarra | viola2, violão3 4 | Spanish guitar |
| guitarra portuguesa | guitarra | Portuguese guitar |
| cenar | jantar | late dinner |
| Spanish word | Portuguese word | English meaning |
| ancho | largo | wide |
| anchura | largura | width |
| largo | comprido | long |
| largura | comprimento | length |
| complemento | complemento | complemento |
| basura | lixo | waste, garbage |
| recordar | lembrar, recordar | remind, remember |
| despertar | acordar | wake up |
| tienda | loja | shop |
| tienda | tenda | tent |
| Spanish word | Portuguese word | English meaning |
| lejos | longe | far away |
| cerca | perto | close by |
| albahaca | manjericão | basil |
| más | mais | more |
| pero | mas | but |
| perro | cão | dog |
| pasta | massa | pasta |
| ahorrar | poupar | save |
| Spanish word | Portuguese word | English meaning |
| cambiar | mudar 5 | to change |
| nada | nada | nothing |
| nadie | ninguém | nobody |
| alguién | alguém | somebody |
| nido | ninho | nest |
| niño | menino | child, boy |
| gracias | obrigado | thank you |
| gafas, anteojos | óculos | glasses |
| ayer | ontém | yesterday |
| quizá, quizás | pode ser| maybe, perhaps | |
| talvez | tal vez| maybe, perhaps | |
| Spanish word | Portuguese word | English meaning |
| vale | pois| right, OK | |
| aunque | porém etc. | however |
| buscar | procurar, encontrar | (try to) find |
| ir por, buscar, sacar | buscar | go get |
| encontrar, hallar | encontrar | find |
| pensar | achar | have the opinion |
| calle | rua | street |
| teléfono | telefone | telephone; same origin, almost the same word, but different stress |
| falda | saia | skirt |
| haber + participio | ter + particípio | (see grammars) |
| volver | voltar | return |
| tener ganas | ter vontade | to feel like (doing) |
pt Gosto de ti = en I love you
es (Tú) gustas a mi = en I like you
Confer the es vihuela, which is clearly cognate with pt viola, and denotes an old guitar-like shaped instrument.
Violão is more likely to be used in pt-BR than in pt-PT.
Note that in pt-BR violinista is a violin player, but a violonista is a guitar player.
In many cases, both words do exist in both languages, but the frequency of use and the shades of meaning are rather different.
I have a feeling there must be many more such words, so suggestions and corrections will be appreciated.
See also these false friends.
See also this list of Galician-Portuguese words.