What causes variation between two breeds of cattle?

Variation between two breeds of cattle is primarily caused by genetic differences, which arise from selective breeding practices aimed at enhancing specific traits such as size, milk production, or disease resistance. Environmental factors, including nutrition, climate, and management practices, also play a significant role in shaping the characteristics of each breed. Additionally, adaptations to different geographical regions and historical breeding choices contribute to the distinct physical and behavioral traits observed in various cattle breeds.