(1)however：主要强调通过增加某个令人吃惊或者进行比较的情况/评论对前面动作加以说明和修正。（强调对比让步关系）

(2)instead 主要强调做出另外一个不同之前的一个选择。（强调取舍关系）

(1)however adv.然而;不过;仍然 (英文解释：You use however when you are adding a comment which is surprising or which contrasts with what has just been said.）

This was not an easy decision. It is, however, a decision that we feel is dictated by our duty. 

这很难抉择。不过，我们觉得自己有义务作出决定。

Some of the food crops failed. However, the cotton did quite well. 

有些粮食作物歉收。但棉花的收成仍相当不错。

(2)instead  adv.作为替代;反而;相反地 (英文解释：If you do not do something, but do something else instead, you do the second thing and not the first thing, as the result of a choice or a change of behaviour.

He reached for the wine but did not drink, pushed it, instead, across the table towards Joanna.  

他伸手拿酒却没有喝,而是把它推给了坐在桌子对面的乔安娜。

下面文章主要厚脸皮的人和薄眼皮的人进行比较，因此用however

There are many ways to describe people using the word "skin." If someone is thick-skinned they are not easily hurt emotionally. You can criticize them or be unkind to them and it simply rolls off their back. Thin-skinned people,   however , are easily hurt by criticism, even if it is not too severe. You have to be careful about  what   you say to thin-skinned people so as not to hurt their feelings.

(1)thick-skinned adj.  厚皮的; 厚脸皮的; 感觉迟钝的; 不知羞耻的

He was thick-skinned enough to cope with her taunts.  

他脸皮厚，不怕她嘲弄。