Greek art and Roman art are both commonly referred to as "classical art." The three primary areas of classical art are painting, architecture and sculpture. Although you will see many similarities between Greek and Roman art, the differences are both interesting and significant for identification. Historically, the Greeks were the primary influences of the Romans in terms of artwork. Although the Romans conquered the Greeks in 146 B.C., their art depended upon the Greek techniques and used similar materials. However, the Romans were also able to step outside the Greek mould and develop original techniques to express their distinctive ideals and values.
The idealistic differences between the Greeks and Romans are perhaps what cause the differences in technique. The Greeks believed that art was an expression of perfection. They sought to encapsulate the perfect physical form of their objects in artwork. The Greeks often represented the gods in their art, in an effort to express the ideal form of beauty, physical strength and power. For the Romans, however, art had a more practical function. Artwork was primarily used for ornamentation and decoration. As noted at the History for Kids website, the Greeks were interested in ideals while the Romans were interested in reality. These fundamental idealistic differences are visible in their artwork.
Greek sculpture tended to focus on athleticism and mythology. Their statues represent their objects in an idealised fashion, making them quite unrealistic though beautiful. The Romans preferred to sculpt historical events and real people and are famous for their detailed busts. If a Roman statue is idealised, it is probably a statue of one of the many Roman emperors, who were considered to be divinities.
The most obvious difference between Greek and Roman architecture is the material used. The Greeks used marble; the Romans used concrete. An excellent way to illustrate the differences between Roman and Greek art would be to study the Parthenon (Greek) and the Pantheon (Roman), which are considered to be the most famous temples of either group.
According to the International World History Project's online article, "Greek and Roman Art," the Romans were most creative in the area of painting. While the Greeks were most developed in the area of vase painting, the Romans created colourful painted murals, some of which are still intact. Painted portraits were also quite popular in Roman times.