East/West vs. Eastern/Western

Obviously, eastern/western cannot be used as nouns, whereas it seems that east/west , while usually utilized as nouns, can also serve as adjectives. For example, geographic regions in Europe are usually called "Eastern Europe," "Western Europe," e.g.; however, I have heard people say "East Europe," etc.

In the United States, one calls the two coasts the East and West Coasts, but never the Eastern or Western coasts. Is this more a matter of a title randomly becoming the norm, or is there a slight difference in the way the adjectives are being utilized in the instances of "Eastern Europe" vs. the "East Coast"? One possibility is that east & west are used when indicating extremes, not degrees, in regard to direction. Allow me to illustrate this: Eastern Europe refers to a region in which there are countries that vary in how east they are,whereas, in the U.S., all of the states which lie on the east/west coasts are pretty much aligned. For example, Poland is less east than Russia, but Oregon and California, two of the three states that make up the west coast, are along the same coastline. Therefore Poland and its respective Eastern European nations are relatively Eastern, whereas there is no question that New York and, say, Florida are precisely on the east coast.