I have a doubt on the difference between series and parallel connected capacitors. Suppose that two capacitors $C_1$ and $C_2$ are charged at two potentials $V_1$ and $V_2$, then they are connected in two different ways
$(a)$ respective positive and negative sides are connected (they are connected in parallel)
$(b)$ positive side are connected with negative sides (they are connected in series)
The picture shows the situations $(a)$ and $(b)$
Now situation $(a)$ is quite clear to me, since they are connected in parallel, they will reach the same $\Delta V$ and the initial charge will be restributed in such what that $\Delta V$ is the same for both capacitors.
But what about situation $(b)$? On textbook it is said that such situation is the same as $(a)$ (same $\Delta V$ for both capacitors) except that the numerical values are different. How is that possible?
I was convinced that if two capacitors are connected in series they will not have the same $\Delta V$ but the same $Q$. But here this seems to be wrong.
So I would like to know what does happen precisely in situation $(b)$. Do capacitors have the same $\Delta V$, do they have the same $Q$, and why?
I really appreciate any help, since this is confusing me quite a lot.