这恰恰是个短语。请看下面的注释。
作为作家,我跟E.B.White不是一个档次/水平。(我不如他)
(idm 习语) in a class of one's/its `own; in a class by oneself/itself :better than everyone/anything else of his/its kind; unequalled 独一无二; 无以伦比:
Pele was in a class of his own as a footballer. 贝利是举世无双的足球健将.
class:
set of people, animals or things grouped together, esp according to quality 级, 等, 等级, 种类(尤指按质量划分的):
As an actress Jane is not in the same class as (ie is not as good as) Susan. 作为演员, 简不如苏珊.