The mobile-friendly website is something that is designed especially for mobiles, while responsive sites are those which adjust layout according to the device.
A mobile-friendly Website is a website that is made for small screens such as Android phones, ios, or any smartphones so that visibility will have more transparency and the readability will be clearer.
A mobile-friendly website affects various things such as text. It will be large with respect to laptops and tablets. The size of the image will get reduced but will be more understandable. Overall user experience(UX) will be good.