what is the architectural difference between the roman and greek building styles ect.

Check these sites for the differences between Greek and Roman architecture.

http://en.wikipedia.org/wiki/Architecture_of_Ancient_Greece

http://www.crystalinks.com/greekarchitecture.html

http://www.iol.ie/~coolmine/typ/romans/archie2.html

http://www.2020site.org/rome/index.html