What are the safety features to consider when choosing between bike and ski helmets?

When choosing between bike and ski helmets, consider safety features such as impact protection, fit and comfort, ventilation, and certification standards. Look for helmets with durable outer shells, impact-absorbing liners, adjustable straps for a secure fit, and adequate ventilation to prevent overheating. Make sure the helmet meets safety standards like CPSC for biking and ASTM for skiing.