Cancun

Cancun is a very big town by the sea compared to Playa del Carmen with big hotels by the beach. Everything is huge, buildings, shopping malls, big avenues, big waves, nothing is within the walking distance but there are public buses that drive around the hotel zone to the Cancun Downtown. I didn't like Cancun as much as Playa del Carmen. 
The place that i found nice in Cancun was the El Rey Mayan ruins at the 17th km of the hotel zone. There were any iguanas walking around the site, often popped up from a hole in the ruin stones. 

There was a great restaurant in Cancun hotel zone called Natura, in front of Senor Frog.

Food was delicious especially the fajitas de pollo. The burritoes were nice too.

El Rey ruins