He furtively glanced behind him, for fear of his imagined pursuers , then hurriedly walked on , jumping at the slightest sound even of a leaf crackling under his own foot. tone and mood and context clues

Tone refers to the author's viewpoint of the situation--the way they feel about what's happening in the story.
Mood refers to the way the character is feeling.

The tone and mood in this passage are different, because the character clearly feels frightened--the mood is scary or spooky. We know this because he is looking around him quickly and jumping at every little sound. 

The tone is a little lighter. The author is showing that he doesn't think there is anything for the character to worry about because he uses words like "imagined" and makes it seem silly for the character to jump at just a leaf under his foot.