One interesting thing about Portuguese and Spanish is that the comprehension isn't symmetrical: Portuguese speakers understand Spanish ones all right, but vice versa is a bit of a struggle.
That effect is far less strong with Brazilian Portuguese, which is much more easily understood by other Latin language speakers.
In fairness, Brazilians often also struggle to understand Portuguese as spoken in Portugal. I (native Spanish speaker from South America) can understand Brazilian Portuguese pretty well, even if I've never studied it. Portuguese from Portugal, I cannot really understand when spoken. It sounds very similar to Galician, which I also can't really understand.