by oneself 与 oneself 与 on one s own的区别

by oneself 和 on one's own 的意思相同，都是“ 独自， 单独” 的意思
一般可以互换且放在句末，只是by oneself 中的oneself 是反身代词，on one's own 中的 one's 是用形容词性物主代词。

如
1 He can finish the work by himself .
= He can finish the work on his own.
他可以自己完成这项工作。

2 Lucy often goes to school by herself .
= Lucy often goes to school on her own .
露丝经常独自上学。

by oneself: 自己做
eg: I will do it by myself. 我会自己做这件事的。

oneself: 反身代词，自己，本身
eg: myself/himself/herself/itself/theirself: 我自己，他自己，她自己，它自己，他们自己
I like the story itself, but I don't like the structure.我喜欢这个故事本身，但是不喜欢它的结构。

on one's own: 自己花销
eg: I will buy the dress on my own.我会自己花钱买这条裙子的。

供参考！