Answer:
The most obvious similarity between Greek and Roman architecture is the use of the Doric, Ionic and Corinthian orders. Though the Greeks developed the Corinthian order, the Romans seemed to have favored it more and constructed more buildings using that order than the Greeks did.
Greeks used sculptures of the human form in their architecture while Romans focused more on the design and technique of the building. Greeks believed in Pagan Gods. Romans imitated the mythological and religious ideologies of Greeks but translated them into a Roman setup.