Is Spanish cuisine and Portuguese cuisine almost the same?

I remember once going to a Portuguese restaurant in Newark, NJ and having a paella which to me looked and tasted exactly like the traditional Spanish one. I thought to myself, Spain and Portugal are both in Iberia and right next to each other. It only makes sense that their cuisine seems identical to me. Are there major differences between Spanish and Portuguese dishes that look the same? Native Spaniards or Portuguese please reply. Thanks.