after all ：1.毕竟,例句：
After all,I am defeated by him.
我毕竟打不过他.
After all,no one knows me better than me.
毕竟,没有哪一个人比自己更了解自己.
2.终究,例句：
The forces for peace,justice and progress are invincible after all.
和平的力量,正义的力量,进步的力量,终究是不可战胜的.
Those American Girls were not so “American” after all.
“美国女孩”终究也不那么原汁原味了.
on earth ：究竟,例句：
What on earth have you done to poor Mr.Darcy?
你究竟对可怜的达西先生作了些什么?.
When on earth did you come?
你究竟什么时候来的?
毕竟：表示追根究底所得的结论.“毕竟”常用在肯定句中,强调原因或结果.
究竟：表示深入研究结果,到底的意思,常用在疑问句中.
综上,after all和on earth是有区别的.