display size is the display height, weight, shape, radius, etc. This is the size of something called a magnifier. Size is most important for the smartphone. There are a lot of smartphone users they have different types of size demand. Thinking about them, according to their needs all mobile companies made the different sizes of a phone. Every customer demand is different. That’s why mobile companies made different types, size, phone.
Some people want to big display size, some people want a small display, some people want to use medium display size, for this reason, the mobile company made different types of size.