On some of the cake shows cake artist when frosting their cakes use the words pastry cream and buttercream does these words have the same meaning.

I haven't heard that, but in the culinary world as far as I know pastry cream or creme patissierie, is more of a pastry/cake filling, like lemon curd would be. You can use it to fill cream puffs, eclairs and cakes like you would a boston cream pie. I wouldn't think with most recipes it would be good for the outside covering, it contains a lot of milk.
But, maybe the word is interchangeable to some, just like some buttercream doesn't contain butter!

No, pastry cream is NOT the same thing as buttercream. Pastry cream is a type of cooked custard. It is for filling, not for icing.

Malakin,Prterrell, thanks for your assistance