Taking their statements at face value, there isn't a correlation between Submitted->Complete and interview. I had an adcom interview about 4 weeks ago, and mine just changed to the following:
All the required elements of your application are complete.
If your interview has been completed, the application has been submitted for review to the admissions committee. If your interview has not been conducted, the application will be submitted to the admissions committee upon completion of the interview.
If your interview has been completed, the application has been submitted for review to the admissions committee. If your interview has not been conducted, the application will be submitted to the admissions committee upon completion of the interview.