Aruba vs Costa Rica?
I haven't been to either, but I have a friend who was living in Costa Rica for a while. They said that it can rain a lot. Some areas can be pretty slummy. The pictures on google are nothing like the pictures they were taking. They did say that it was beautiful though. I remember them talking about some other negative things but I can't remember. Sorry that I couldn't be of more help but I hope that you find some good answers!
Been to both places, if you want to just hang out at the beach go to Aruba. Aruba has a lot cleaner beach and overall I believe a safer place. But I enjoyed both places.
They are very different. Aruba is dry and windy. All Aruba has is a small downtown and beaches. It has great snorkeling. It is safe. They speak English. Costa Rica is hot and humid. It gets a lot of rain. There are mountains, beaches, rainforests, and cities. There is a lot of tourist crime. They speak Spanish.