（1）、作动词时fit 分别可作vt和vi,而suit只作vt,并且suit和fit各有不同的意义.
suit:
1) meet the needs of; be convenient to or be fight for
对……方便,适应……的要求
Will it suit (= ) you if I come at 3:00?
— Does the climate suit you / your heath?
— Yes,it suits me fine.
2) (the color or style of a dress or hair) look well
（指衣服、发型等）相配；适合
— Does this skirt suit me
— The color doesn't suit you.
fit:be the right size or shape (衣服、鞋子等尺码大小,形状等)合适；合身
The door fits badly.(vi)
The coat fits me well,but the color doesn't suit my trousers.
这衣服很合身,但颜色与我的裤子没配好.
在上一句里suit和fit不能互换,因为由上可知fit只指“尺码大小合脚,合身”等,而suit指“衣服、颜色、发型等相搭配”.如下句：
The job doesn't fit me.(×)
The job doesn't suit me.(√)
（2）作形容词时be fit for 与 be suitable for 可互换.
The job is not fit / suitable for me.
