厚此薄彼 is formed by combining two verb-object phrases: 厚此 (favor this) and 薄彼 (slight that). The characters 厚 and 薄 are antonyms meaning "to favor" and "to slight", respectively, while 此 and 彼 are demonstrative pronouns meaning "this" and "that". This juxtaposition creates a contrasting structure that literally means "favor this and slight that", directly conveying the concept of unequal treatment.