If you are staying in Tulum, obviously Tulum ruins are much closer than Chichen Itza
Tulum, on the other hand, does not have world wonder status, but the location of the Tulum ruins on a cliff overlooking the sea is absolutely stunning.
You can arrange Chichen Itza tours from basically anywhere in the Yucatan, the most popular being tours from Cancun, Playa del Carmen, Tulum, Merida and Valladolid.
If you come to Tulum by bus or collectivo from Cancun or Playa del Carmen, they usually drop you off on the main road going through Tulum, which is a 10-15 minute walk from the entrance to the ruins.