這三個(gè)詞組用法是類似的：
to some degree也作to a degree,與to some extent是一個(gè)意思,意為‘partly'
to a/some degree的例句:
To some degree I think that's right,but there are other factors which affect the situation
to some extent的例句：
To some extent,she was responsible for the accident.
以上參考：The Cambridge Advanced Learner's Dictionary
在The Cambridge Advanced Learner's Dictionary中未收錄'in a way'這一詞組.在GOOGLE中顯示in a way在使用上確實(shí)不如這兩個(gè)詞組普遍.
In a way意為To a certain extent,with reservations; in some respects.
例句：
In a way I like the new styles.
You're right,in a way; but we have to consider the price.
可以看出,如果用'in a way'的話,這上面兩個(gè)例句中,是可以用另外兩個(gè)詞組代替的.使用上沒有區(qū)別.