So, is it really the same? DR and PR (dominicans and puerto ricans??)?

I was wondering if Puerto Ricans and Dominicans can understand eachother's spanish better than anyother spanish speaking country since they are so close to eachother. I am spaniard so I speak straight up castellano, and when I hear other spanish people talking, they talk alot slower than i'm used to hearing, because i speak it very fast and so does my fam so im used to fast talking. but anyways, do they have more similar words than different?? and can they understand castellano spanish in any way?