both models have good performance but some points can make the difference between these two models which is
Samsung galaxy M20 have 25% more Battery Capacity
samsung galaxy have 13MP + 5 MP Camera
Android v8.1 (Oreo)
Better screen resolution.
If you are going to buy new phone One important thing always remember To protect the screen with back cover ...I will suggest you one good website of latest covers. https://www.hamee-india.com/