It depends on what time you're thinking of. The Roman empire began relatively small and then grew as Romans began their conquest of the area around them. This is why there are Roman walls in England...
They're not the same, however the Romans adopted a lot of Greek ideas and integrated with their own. The Greeks invented catapults, and the Romans improved on it and invented the 'ballista.' The...
Sicily was owned by both, at separate times, though. Sicily was a colony of Greece, even though it is geographically closer to Carthage, who owned part of it. Then, the Romans fought for it and...