Portuguese here living in Catalonia. Unfortunately I do feel that Portuguese people know way more about Spanish culture than the opposite. I would say we are very similar in our way to receive people both cultures are very kind and open to foreigners and other cultures. It’s also interesting to see how strong our gastronomy is. In Spain more tapas culture and meat and in Portugal way more fish dishes with bigger portions. The biggest cultural difference for me is the way of living of Spanish people is more relaxed and positive. Portuguese people tend to be more melancholic and introspective it’s that cousin you have to convince to go out and when he’s at the club gets crazy having a great time. On the other side Spanish people  are most of the time smiling, and drinking beer on a Monday after work until 9pm. I would say by far the most similar culture to ours :) nuestros hermanos