In a rules-bound society, it's easy to conflate etiquette with manners. It doesn't help when "manners" is used freely to also mean "etiquette".
Etiquette is all those rules about who is introduced to whom, which fork is used for what, what title one uses to address others, how one dresses for which occasions, what topics of conversation are suitable at each event, and so on. Etiquette is a matter of memorizing the rules and then following them. Following the etiquette rules doesn't make a person well-mannered.
Manners cross etiquette lines and social lines - a well-mannered person is comfortable in unfamiliar situations and with people from all walks of life and all cultures. A well-mannered person will be forgiven a great many breaches of etiquette, but it's much harder to forgive an ill-mannered person even when they meticulously adhere to each and every etiquette dictate.
Manners is not "general behavioral guidelines" because that can be interpreted in many ways, not all of which are what one would consider good manners. Modern general behavioral guidelines seem to allow for a great deal of selfishness and self-indulgence at the expense of those about them. "What? I was only doing what everyone else does!" No, "general behavioral guidelines" just doesn't measure up to proper good manners. It is a wimp of a definition that manages to provide no information whatsoever, and it's a cop-out used by those who don't know what manners really is.
Manners is compromised of actions based on consideration for others.
A recent example of good manners is being provided by thefatladysings and peregrine kate and "Cali Scribe* who are organizing the disability accommodations for those who are attending Netroots Nation and have challenges of various sorts. They don't have to do this - the facilities should already be ADA compliant and have accommodations in place. NN doesn't have to make sure those accommodations are adequate, that the transition from one programming space to another is smooth and easy for those attendees with disabilities, or that the relaxation and play spaces are not just accommodating but welcoming to those with challenges. That's good manners, taking those steps based on consideration for others.
I believe that manners have been lost because the definition has been so watered down and it's been so conflated with etiquette that few people understand what manners truly is. Dictionary definitons, usually so helpful, fail us in this regard
a. The socially correct way of acting; etiquette.
b. The prevailing customs, social conduct, and norms of a specific society, period, or group, especially as the subject of a literary work. - free dictionary
1. social conduct he has the manners of a pig
2. a socially acceptable way of behaving - MacMillan Dictionary
2 a (1) : a characteristic or customary mode of acting : custom (2) : a mode of procedure or way of acting : fashion (3) : method of artistic execution or mode of presentation : style
b plural : social conduct or rules of conduct as shown in the prevalent customs
c : characteristic or distinctive bearing, air, or deportment
d plural (1) : habitual conduct or deportment : behavior (2) : good manners - Merriam Webster
1 [man-er] Show IPA
1.a way of doing, being done, or happening; mode of action, occurrence, etc.: I don't like the manner in which he complained.
a. the prevailing customs, ways of living, and habits of a people, class, period, etc.; mores: The novels of Jane Austen are concerned with the manners of her time.
b. ways of behaving with reference to polite standards; social comportment: That child has good manners.
3. a person's outward bearing; way of speaking to and treating others: She has a charming manner. dictionary.com
2a person’s outward bearing or way of behaving toward others:his arrogance and pompous manner a shy and diffident mannerThese definitions give you an idea of what manners might be through description of some of the outward reflections of what good manners are, but every one of them leaves out the most important part of the definition, the defining part, as it were - that manners are predicated upon consideration for others.
3 (manners) polite or well-bred social behavior:didn’t your mother teach you any manners?
social behavior or habits:Tim apologized for his son’s bad manners - Oxford Dictionary
Take other people out of the equation, and there would be no need for manners at all.
But we don't live in a society where we have zero interaction with any other living creatures. We have neighbors, co-workers, family, friends, strangers, tourists, visitors, and any number of other people all around. Etiquette rules help us do things that smooth the way for others, including set phrases like "please" and "thank you".
What really makes societies work, though, is manners. Manners arose from the innate desire to please others and to make them comfortable. In a well-mannered society, everyone would consider the needs and feelings of others and the social chastisements of a cold shoulder, the cut direct, and even ostracization would work to remind people that consideration of others is the heart and core of good manners.
Jane Austen's novel "Emma" exemplifies the difference between "etiquette" and "manners" - Emma herself is filled with etiquette but not manners, while her friend George Knightley, is a man of impeccable manners as well as etiquette. His lessons to Emma are very insightful in teaching her manners, which she does learn by the end of the novel. The movie holds fairly close to this as well, so watching the movie would be as instructional as reading the novel.
Another lesson in the novel (and movie) is that when one breaches good manners, there is a path back to acceptance. It's not an easy path, and it takes time to achieve, but it can be done.
The third lesson is that even rich, privileged people need and can learn good manners.
A society that embraces good manners, consideration for others, as the standard of social conduct is a society that is vibrant, growing, and adventurous. They can flourish artistically, innovatively, scientifically because even though their eccentricities and habits may not conform to etiquette standards, their attitudes conform to good manners.
Well, except for evil overlords, but history shows us that evil overlords are overcome in the end after a bit of excitement. After all, evil overlords eventually forget their manners and display only etiquette.