噁心的使用範圍較廣，食物、話語、不討喜的人事物都可以使用噁心，I think the closet English translation would be disgusting. (more negative; can used in a cute way) 肉麻通常用於情侶間的話語、情書等。(neutral to slightly positive) The English translation might be excessively romantic; sappy; mushy Reference: http://www.chtoen.com/%E8%82%89%E9%BA%BB%E7%9A%84%E8%8B%B1%E6%96%87%E6%80%8E%E9%BA%BC%E8%AA%AA The link is also for your reference.

恶心 = nausea 肉麻 = causing goose pimples, whether in good or bad situation.

恶心，的恶读三声，是指人的心或感觉，感受很不舒服，甚至想要吐的感觉。 肉麻，就是字面意思，这里的肉一般指人的体表皮肤，比如，他吓得头皮发麻。麻，比如人蹲在地上时间长了脚，腿都会发麻，或过电的感觉。肉麻首先就是字面单字，感觉身上的皮肉发麻。那么为什么发麻？就是听到了自己认为的过分的话，比如过分亲密等等的话。

恶心 means someon says something what meakes you uncomfortable, for example, when you are eating something, someone is vomiting in front of you, at this time, you don't want to eat anymore due to this. 肉麻 means i say to Mary in front of you: Mary, you are pretty, very beautiful, i like you, l love you very much.

程度有所不同吧。 肉麻通常是情侣之间，做一些虐狗的事情，另外拍老板的马屁也可能会肉麻； 恶心这个词范围就广了，肉麻到极致就是恶心，吃汉堡吃出一个蚂蚁也很恶心