Did Greece and Rome exist at the same time? Or did Rome assimilate Greece into it?

Answer 1

The Greek empire under Alexander the Great rose and faded fairly quickly. The Romans rose more slowly, but had a better organization and they incorporated Greek culture into their own. The Romans faded more slowly, too, because the bureaucracy held the core of it together for centuries and was gradually replaced by the Roman Catholic priesthood.

Answer 2

Greece was an older civilisation than Rome and Rome used much of greek culture

Answer 3

Of course they did.