Etiquette is a code of conduct that defines appropriate social behavior. Manners are standards of conduct that demonstrate a person is proper, polite and refined. What is considered mannerly is subject to change based upon time, location, occasion, situation, social status, and various other factors.
While some people feel that following etiquette is a restriction on their freedom of personal expression. Other people find following etiquette easier than having no protocol and that doing so reduces misunderstandings and increases courtesy.
The simple way to think of it is that using etiquette and manners transforms men and women into gentlemen and ladies. If that sounds attractive to you, you may be well served by learning how to practice etiquette and display good manners.