There is a big difference between pretty and beautiful, but most times, people end up using the words interchangeably. This might not be unconnected with the fact that the two words are used to refer to something that appeals much to one's eyes. In a more profound sense, pretty is not the same as beautiful and pretty is used in other contexts that are not necessarily about appreciating the physical appearance of someone.
Pretty is an adjective used to describe something so pleasant insight? It is used mostly for women and children to understand their physical appearance. When a guy tells you that you look pretty, it means you are good-looking.
Beautiful, on the other hand, has a deeper meaning than pretty. It is used to describe women with excellent stunning looks, and they are not only appealing to your eyes but also your soul. Also, at times, a man can describe a woman as beautiful not because she is gorgeous but because she is just an embodiment of knowledge.