The only work of Dickens that I know of that has two different endings is Great Expectations. So I have moved this question to that group. I hope that is what you were asking about.
The major difference between the two endings has to do with what happens with Pip and Estella. In Dickens' original ending, it is clear that Pip and Estella will never get together. Estella marries someone else and it appears that she and Pip will never see one another again, let alone be in love with one another.
In the second ending, we are not specifically told what becomes of the two of them. However, the last line in this version strongly implies they will end up together:
I took her hand in mine, and we went out of the ruined place; and, as the morning mists had risen long ago when I first left the forge, so, the evening mists were rising now, and in all the broad expanse of tranquil light they showed to me, I saw no shadow of another parting from her.
This is, of course, a very significant difference in the ending of the book.