Impressions of Ancient Greece and Roman

Illustration for different between Roman and Greece (credit to Google)

I knew several mythological gods; statues and architectural building, but that confused me whether belongs to ancient Greece or Roman. 

As always, many times I mixed up the different between Zeus and Jupiter; Poseidon and Neptune; Hades and Pluto; and Hermes and Mercury. 

Then, in term of statues; the beauty, medium and heroic quality of Greece and Rome sculptures looks the same for me. 

In respect to architectural buildings, since they were characterized by pillars to support in front roof, I thought they are exactly similar in size and style.

However, recently, my impression is quite little bit changes in ancient culture. I understand now that Romans assimilated Greece in many ways (aspects) due to their long time to occupy the Greece. 

Even though, as conquerors, Roman structures and paintings have strong human values. In addition to totally copy of Greece, then Romans has their own conception too. They also combine the Greek and their own arts. 

As an early stage of understanding art history, I myself feel that Parthenon and Pantheon have helped my changed of thought to ancient Greece and Roman cultures.

Both architectural buildings have similarities in term of initial function and number of columns in front of the entrance. 

Some of different that the building is the Pantheon for serving many gods, while Parthenon for one god only, Athena; and the Parthenon is a rectangular form, while Pantheon is built in a spherical structure.

What do you know about different between Roman and Greece?