If you recently started exercising then it is better to begin your weight loss journey with walking. Once you get into the routine, increase your pace to burn more calories. After a week or two, you can switch to running. You can also try interval running that can help you burn a massive amount of calories.
If you are above 50 or suffering from any heart problem or joint and muscle pain then walking is better for you. Running is a hip-impact activity that may put a lot of pressure on your body, making your condition worse.