Hello BonBon,
They are quite similar ,but you won't get confused on the long run.
The more you practice each separately, the more you would be able to distinguish the similarities and not mix up the spelling in both languages.
If you learned them simultaneously but put more effort into one of them , you will notice that you will make more mistakes in the other language and tend to use more vocabulary from the language you are studying more, when using the other one.
It is recommendable to learn them both at the same path and with time you will be able to effortlessly use each one with distinctness and minor confusion.