As for the difference between lejos and lejano, "lejos" is an adverb meaning "far/far away" it will be acompanied by a verb, for example: "Yo trabajo lejos del centro" (I work far away from the centre), while "lejano" is an adjective that will accompany a noun. It also means far/far away. For example: "Ella vive en una ciudad lejana" (She lives in a far away city.) As an adjective, it will need to agree with the noun it is referring to [lejano, lejana, lejanos, lejanas].
LEJOS / FAR follows a little boy as he explores the world around him, starting with the wide-open landscape right outside his home -- "El árbol de limones está lejos de mi casa." He moves on to "My house is far from the city" and ventures off with his dad to explore the world outside his fenced-in yard. He visits the city and travels to the ocean and mountains. Along the way he makes observations of what is far -- "The ocean is far from the mountains." This engaging little book ends with the introduction of a new concept -- over -- when the little boy says, "The sun shines over me."
Both tend to appear within the predicate, after verbs like "estar", "encontrarse" or "quedar", but "lejos" is much more usual and "alejado/a/s" can sound a little more formal or literary. Also note that the verb "quedar" is only used for things.
There is an important difference between "lejos" and "alejado/a/s" and that is that "lejos" can refer to a temporary/occasional or permanent distance, while "alejado/a/s" almost always refers to a permanent distance and will thus tend to be used for properties or locations being far from other places.
Note: "estar alejado" (NOT "estar lejos") can be used for a temporary, emotional rather than physical distance, though in this case I prefer "estar distanciado", e.g. Estoy alejado / distanciado de mi familia (I am estranged from my family). 041b061a72