一、都可以表示轉折
I like sports but I don't like swimming.
我喜歡運動，但我不喜歡遊泳。
She is young but very experienced.
她雖然很年輕，但很有經驗。
換成however：
I like sports，however，I don't like swimming.
我喜歡運動，但我不喜歡遊泳。
She is young, however，she's very experienced.
她雖然很年輕，但很有經驗。
二、都可以表示對比
She is beautiful，but not as smart as you are.
她是漂亮，但她沒你聰明啊。
She is beautiful，however，she's not as smart as you are.
她是漂亮，但她沒你聰明啊。
不同點：
1、連接兩個句子時，but可以直接帶句子，however後面需要用逗號「，」與句子隔開，見上述例子。
2、「but」可以連接句子和詞、短語；「however」一般只跟句子。
He looks small but healthy.
他看起來個子雖小但很健康。
but可以連接兩個詞，但是改成用however的話，就只能用句子。
He looks small，however，he's very healthy.
他看起來個子雖小但很健康。
3、「however」的位置比「but」靈活。
He hasn't arrived yet. However，he will come soon.
He hasn't arrived yet. He will, however, come soon.
He hasn't arrived yet. He will come soon, however.
他現在還沒到，但是他很快就會到了。
however可以放在句子的句首、中間，或最後。
He looks small but healthy.
He looks small，but he's healthy.
他看起來個子雖小，但很健康。
but一般只放在它連接的句子的句首；或者在連接兩個並列詞組時，房子中間。
4、「however」可以表示驚奇或強調，「but」不能。
However did you get here without a car?
沒有汽車你究竟是怎樣來的呢?
5、「however」可以引導讓步狀語從句，「but」不能。
However it may be, I shall take your word.
無論如何，我將會相信你的話。
However what you do, I won't forgive you.
無論你做什麼，我都不會原諒你。