1. They don't speak Spanish
The Portuguese don’t speak Spanish. They speak Portuguese.
The Romans brought Vulgar Latin over to the Iberian Peninsula (i.e. where Spain and Portugal are) in the 3rd century BC, and this was still being spoken all over Portugal by the 13th century AD. In 1290, King Denis of Portugal decided to make Vulgar Latin the official language of Portugal, calling it ‘Portuguese’.
There are up to 220 million native speakers of Portuguese around the world, making it the sixth most popular language worldwide. Yes, it is similar to Spanish (Speakt reckons the two languages share a lexical similarity of 90%), but Spaniards still have a tough time understanding Portuguese speakers, and vice versa.