How did Greek religion differ from Greek mythology?

While Greek religion and Greek mythology are closely interlinked, they are distinct concepts. Greek religion refers to the actual religious beliefs, practices, and cultic activities of the ancient Hellenes, whereas Greek mythology is concerned with the traditional tales and narratives regarding gods and heroes.1

The primary differences include:

• Nature and Focus: Greek religion was centered on the belief that gods existed and the necessity of performing ritual and sacrifice to secure divine favor. In contrast, mythology provided a large corpus of stories that embodied the worldview of the culture, though these myths were often subject to change by writers and poets.12
• Institutional Structure: Greek religion lacked a formal clergy and sacred books; priests were primarily responsible for maintaining cults. Mythology, however, existed as a literary and oral tradition that could be critiqued or altered on ethical or artistic grounds.13
• Practice vs. Narrative: While some myths were directly connected to rituals, many others existed independently of cultic practice. Cultic activity was generally conservative and persistent, even when the original meanings of certain practices were no longer understood by the worshippers, whereas the myths themselves were fluid and evolved over time.413