Setting adds color to the story, affects characters, adds authenticity to the narrative and paints pictures in the imagination of readers.--Nancy Lamb, The Art and Craft of Story Telling.
Settings aren't just backdrops. Just by where you have the action happening will tell a lot about the action itself and the people involved.--Ansen Dibell, Plot.
Setting grounds your writing in the reality of place and depicts the theme of your story through powerful metaphor. Without setting, characters are simply there, in a vacuum, with no reason to act and most importantly, no reason to care. Without a place there is no story.--Nina Munteanu, scribophile.Landscape - the broad vista.
On the surface, it would appear that landscape and setting are the same creatures, identical twins given different names just to confuse the beginning writer. This, however, would not be the truth since setting is where a story takes place--including where each scene takes place--while landscape is much broader than that . . . Landscape in writing implies much the same as that which is implied by the word when it's used to refer to a location in a country: It is the broad vista into which the writer actually places the individual settings of the novel, sort of like the canvas or other medium onto which a painter has decided to daub color.
You need to think about the landscape of your book because if you're able to make the landscape of place real, you can make the land itself real, which gives you a leg up on making the entire novel real for the reader.Atmosphere - tone and attitude.
Sometimes referring to subject matter, sometimes to technique. Part of the atmosphere of a scene or story is its setting, which includes the locale, period, weather, and time of day. Part of the atmosphere is its 'tone,' and attitude taken by the narrative voice that can be described, not in terms of time and place, but as a quality--sinister, facetious, formal, solemn, wry, and so on . . . As we need to know a character's gender, race, and age, we need to know in what atmosphere she or he operates to understand the significance of the action.--Janet Burroway, Writing Fiction, a Guide to Narrative Craft.Setting, landscape, atmosphere are separate entities but connected. The first puts you in the action. The second contains the story's broader vista. The third enables the characters to breathe.