Voltage level translation between +3V and +3.3V
You actually don't care what the VCC or VDD voltage level is, but are more interested in the V(input lo) and V(input high) requirements for both devices. 

For your 3 V and 3.3 V system elements the real questions are:


When driving the 3 V input from the 3.3 V element output can the output voltage be too high?


For many interface elements the input is advertised as 5 V safe, so for those elements the 3.3 V output can interface directly to the 3 V system.
I'd suggest there are no conditions where this would not work or cause damage.

Some logic has clamp structures in the input gates, so there is more to consider.
For these elements it may look a bit like this:  



Under these conditions (high signal) where the input diode clamps are planar diodes with a Vf of typically 650 mV you unlikely to get current flowing from the 3.3 V output into the 3 V elements VDD structure/supply.
For safety your could add a small value resistor to limit current.  


When driving a high from the 3 V element will V(output high) meet the requirements of the 3.3 V element V(input high). 


Since the V(output high) of the 3 V element will approach 3 V, this will easily meet the requirements which are likely in the 1-1.8 V level. You can directly connect the 3 V element output to the 3.3 V element input.