Waiting is a present participle conjunction of the verb wait and await is also a verb, both have the meaning of delay in expectation of something happening.
While they are similar in terms of meaning they differ in usage. Waiting can be used without an object, like I am waiting. However, await requires an object. In this case Joey is actually using waiting but he is using a dramatic pronunciation to emphasize his impatience. This is something you may hear in casual conversation with friends.