两者的区别在于even though的意思是即使；尽管，在两个从句或句子之间可用此词表示对比。even though多用于口语，可用于句首或带有动词的从句开头；even so的意思是即便如此；尽管这样，在句中相当于插入语，可以省掉，放于句中时，even so的前后都要有逗号，将它和句子隔开。

even so例句：
Even so，things don't always go as planned。即便如此，事情也并不总会按照计划发展。
It has many omissions，even so，it is quite a useful reference book。那本书有许多遗漏之处，即使如此，尚不失为一本有用的参考书。
Even so，some progress has been made。即便如此，还是取得了一些成就。
even though例句：
I will have a try even though I should fail。哪怕失败，我也要试一下。
His mind was clear even though he was very ill。尽管病得很厉害，但他头脑仍很清楚。
Even though he was getting angry，his voice remained level。即使他非常生气，他的声音仍保持稳定。