两者均可表示转折或对比，意为“但是”、“可是”、“然而”等，但有区别：
1. 表示转折时，but 是连词。如：
He is young but very experienced. 他虽年轻，但经验很丰富。
He has three daughters but no sons. 他有3 个女儿，但没有儿子。
He likes sports, but his wife likes music. 他喜欢运动，而他妻子则喜欢音乐。
2. however 表示“然而”、“可是”时，有的词书认为它是连词，有的词书认为它是副词。之所以将其视为副词，也许是因为像许多副词一样不仅能位于句首，而且能位于句中(注意前后使用逗号)，甚至句末 (注意其前也用逗号)。如：
Later, however, he changed his mind. 可是他后来改变了主意。
He hasn't arrived. He may, however, come later. 他还没有到，不过他等会儿可能会来。
He said that it was so; he was mistaken, however. 他说情况如此，可是他错了。
注：以上各例中的 however 不能换成 but，但可用 but 来改写。如：
He said that it was so, but he was mistaken. 他说情况如此，可他错了。
3. 当连接两个句子时，其前通常应用分号，或另起新句。如：
It's raining hard; however, I think we should go out. / It's raining hard. However, I think we should go out. 雨下得很大，但我想我们还得出去。
注：上例中的 however 不能换成 but，但可用 but 来改写 (注意所用标点的变化)。如：
It's raining hard, but I think we should go out.
