by contrast 对比起来,相比之下.
例子：By contrast,Mary is much diligent than Tom.相比之下,玛丽比汤姆勤奋得多.
in contrast 与此相反,相比之下
常用短语in contrast with/to和……形成对比,比较起来,后面接名词.
例子：In contrast with their systems,ours seems very old-fashioned.与他们的制度相比,我们的显得太陈旧了.