I really don't know which to choose between the two books./...know to choose which...两句有什么差别吗?

I really don't know which to choose between the two books.
/...know to choose which...
两句有什么差别吗?

i really don't know which to choose between the two books.
我真的不知道该在这两本书中选择哪一本.
i really don't know to choose which two books.
我真的不知道该选择哪两本书.