relish它强调的是"get pleasure"或者"want very much to do …" ，有“享受”、“喜欢”之意，和enjoy特别相近，用法上也是一样的，enjoy / relish + n. / v.-ing / pron.

relish

vt. 品尝，品味;给…加佐料，调味;欣赏

vi. 有滋味;有…的味道

n. 味道，滋味;调味品;引起兴趣的东西

e.g.But they say they can go only so far , so fast without compromising tastes consumers have come to relish or salt 's ability to preserve food .

但他们说在不对消费者喜欢的味道或盐保存食物的功能上作出让步的情况下，他们只能做到这一步，做得这么快。

enjoy的用法

①to get pleasure from sth. 享受……的乐趣;欣赏;喜爱

这个意思和relish没差别了,可以互换。

②oneself: 玩得痛快/开心

enjoy oneself这个结构，我翻了很多例句，并没有发现relish oneself的用法。

另外，enjoy的第三和第四个意思也是relish所没有的。

③[formal] to have sth. good that is an advantage to you 享有;享受

e.g. He's always enjoyed good health

④[informal] used to say that you hope sb. gets pleasure sth. that you are giving them or recommending to them

e.g. Here's the book that I promised you, enjoy it!

In general, 两者的差别可能就在于只有当enjoy取第①个意思时才是可替代的，其他情况下，enjoy的意义是不能被relish替代的。