CCU: ICU or no?

Yes, the CCU I started in is an ICU. I think generally CCUs are considered ICUs, however, this may differ between hospitals/hospital systems. I'm sure there are some that have PCUs, or combined units with intermediate or progressive level patients as well as critical patients. But generally, I believe CCU is an ICU. 

Interchangeable terms, same thing.  

Unit names have become very confusing, especially in cardiac specialties. The easier way is to ask this: Can this unit take care of a patient with an endotracheal tube, fully sedated and on full ventilator support settings? Can you start Levophed and titrate it? If the answer is yes to both of these questions then you are a ICU.

A few places abbreviate their "Cardiac Care Unit" as CCU. This is not nearly the same as a Coronary Care Unit(also CCU) or a Critical Care Unit(also CCU). A Coronary care unit is usually equivalent to a CICU, and they can take fully intubated patients, on pressors, and sometimes on high mechanical circulatory support like Impella and ECMO. In a few institutions, a CCU is a Cardiac Care Unit, which is their version of a cardiothoracic stepdown, which is not an ICU.