While obtaining both types of experience isn't required, it's strongly recommended. It's important to be able to show that you've put in a serious effort to help solidify your decision to pursue medicine. Nothing can demonstrate this better than your clinical experiences.
This is where you'll learn what a typical day in the life of a doctor is like, interact with and care for patients, and understand your responsibilities as a physician. Non-clinical volunteer experience is equally important as it shows the admissions committee that you are not only self-serving.
Demonstrating how you helped elevate your community, that you put others first, and that you value helping others succeed will speak louder than the simple words “I want to help people.”