I assume you are asking what the difference between Kings, Castles, Stars, Saints, Halls, Granges & Manors are. The main difference is in size and weight. My list covers all the 4-6-0 types in descending size order. The different sizes are designed for different types of work. The largest locos are for express passenger traffic, whilst the smaller ones are for mixed traffic. Additionally the smaller ones have better route availability, for example of the locos in the list only a manor can work on the Cambrian coast line, as the others are too heavy for the wooden bridges. There are also a variety of 4-4-2, 2-6-0 and 2-8-0 classes that follow the same kind of design.
GWR locos look similar because the company was a pioneer of using standard parts across many classes.