Lejos vs. lejano

In the Spanish language, the words 'lejos' and 'lejano' share a similar concept related to distance but are used in different contexts.

Lejos

'Lejos' is an adverb used to describe a place, indicating that it is at a considerable distance from a reference point or the speaker.
Vivo lejos de la ciudad.
(I live far from the city.)
Ese país queda muy lejos.
(That country is very far away.)
¿Estamos lejos todavía?
(Are we still far away?)

Lejano

'Lejano' is an adjective that qualifies a noun, meaning that it is far away or refers to something distant in space or time.
El planeta lejano fue descubierto recientemente.
(The distant planet was recently discovered.)
Sueño con viajar a tierras lejanas.
(I dream of traveling to faraway lands.)
En un tiempo lejano, vivían dragones en estas montañas.
(In a distant time, dragons lived in these mountains.)

Summary

'Lejos' and 'lejano' both relate to the concept of significant distance but serve different grammatical functions within a sentence. 'Lejos' is an adverb used to modify verbs, adjectives, or other adverbs, typically answering the question 'where?' 'Lejano', on the other hand, is an adjective used to describe nouns, therefore it changes its form to agree in gender and number with the noun it describes.