It seems that some people see these two concepts as being the same when in all actuality, they are not.
You see I am diabetic. I check my blood sugar periodically with a blood sample and a glucometer. But when I see my doctor, I get an A1c test. The glucometer gives me an instant reading of the blood sugar at that moment. I can test again in an hour and the results will be different. But the A1c test gives a general view over 3 months. Both tests are important because I might be all concerned over the details of each glucometer test but when I see the doctor, I find out that my overall success is actually pretty good.
So what does this have to do with perfection and excellence. Perfection is a goal but it is rarely attainable (some would argue never attainable), but Excellence is the result of reaching for Perfection over time. But just because something is Excellent, doesn't mean it is Perfect. And likewise, just because something isn't Perfect doesn't mean it isn't Excellent.
So the pursuit of Perfection is admirable but not consistantly attainable, because we are all human and make mistakes. But the pursuit of Excellence is attainable, even with flaws.