I’m of Argentinian background and I speak Spanish fluently. Although Italian resembles Spanish is some respects, mainly in accent and some vocabulary, it is not that close to Spanish as many people wrongly believe.

Portuguese on the other hand, is a language that is almost totally compatible with Spanish. Apart from a slightly different accent, Portuguese vocabulary is almost the same as in Spanish. Portuguese grammar is very, very similar to Spanish too.

When I hear Portuguese I always sense a very close proximity to Spanish, a shared same Iberian origin as evidenced in shared expressions, way of sayings things, things only Portuguese and Spanish speakers would understand among themselves. It’s hard to explain. I don’t get this sense when I hear Italian apart from the obvious Latin origin of the languages.

I can’t tell you how many times Italian speakers have tried to engage with me in discussions and only to get confused. A similar accent only goes so far. This is where Portuguese wins the day.

Almost any word that exists in the Spanish dictionary, also exists in the Portuguese one. Some times when we have different word preferences for the same thing we simply introduce another that means the exact same thing. Otherwise, almost all our words are the same. Sometimes they are spelled a tiny bit differently i.e., mangueira vs. manguera (hose) but identically pronounced, or a little differently pronounced but spelled the same i.e., Domingo (Sunday). The order in which we construct our sentences parallel as well: i.e.,
Spanish: yo quiero comer una naranja cinco veces por semana.
Portuguese: eu quero comer uma laranja cinco vezes por semana.
Italian: Voglio mangiare un’arancia cinque volte la settimana.
English: I want to eat an orange five times a week.

Italian being 7% less lexically similar than Portuguese makes a huge difference, and ultimately makes Italian less understandable to Spanish speakers. Our accents sound similar but so what.

On the other hand educated Portuguese and Spanish speakers can converse with each other speaking their own languages and understand one another almost perfectly.

That is not the case between Italian and Spanish, because conversations always end up getting confused because of significant vocabulary, grammar and sentence structure differences.

From the beginning, the Portuguese and Spanish languages and culture have been remarkably close, like brothers, even if at times in past history there were some political tensions. Nowadays we respect each other totally and have a special Iberian relationship.
We were both great former colonial powers and today our languages are spoken by hundreds of millions of people in the world. For the longest time Portugal and Spain were one country. Portuguese and Spanish speakers are very close neighbours here in Europe, South America and Africa.

Spanish speakers are tired of Italians who claim to be the closest linguistically and culturally to us when they are not. It is the Portuguese and Brazilians who are.