Short Answer 
Dr. Jekyll and Mr. Hyde illustrate the duality of human nature, with Dr. Jekyll representing morality and responsibility, while Mr. Hyde embodies chaos and pure evil. Their contrasting ages further emphasize these differences, as Dr. Jekyll is mature and composed, whereas Mr. Hyde is young and impulsive. Ultimately, the characters symbolize the internal struggle between good and evil within a single individual.
Step 1: Character Descriptions
Dr. Jekyll and Mr. Hyde represent two distinct facets of the same individual, highlighting the duality of human nature. Dr. Jekyll is characterized as a tall and composed man, embodying traits of professionalism and morality. In contrast, Mr. Hyde is described as small and menacing, often associated with fear and chaos.
Step 2: Age Differences
Another significant difference is their ages, which contribute to their contrasting personas. Dr. Jekyll is portrayed as an older and more mature character, signifying responsibility and intellect. Meanwhile, Mr. Hyde appears young and impulsive, symbolizing a reckless disregard for societal norms and moral values.
Step 3: Moral Contrasts
The most profound distinction lies in their moral compasses. Dr. Jekyll is depicted as a good and well-intentioned individual, striving for the betterment of society. In stark opposition, Mr. Hyde embodies pure evil, indulging in violent and dark behavior, which showcases the struggle between good and evil within the same person.