The word 级别 is formed by combining two characters, each contributing a core meaning to create a new, unified concept. The character 级 originally depicted steps on a ladder or stairs, conveying the idea of a rank, grade, or hierarchical step. The character 别 carries the fundamental meaning of to separate or to distinguish. Therefore, when combined, 级别 conceptually represents "distinguished ranks" or "separated grades", directly picturing the idea of a structured system of levels or classifications.