Ziggs is a champion whose complete focus is range. The only problem with him, is that your going to have to poke your enemy once or twice before your combo can fully kill them. I mean of course, once fed, he can burst squishies down really fast, but it will take some time to get there. One major thing though is that he is completely skillshot reliant. If you find skillshots in LoL kind of difficult to hit seeing as you're a low level, I might recommend choosing a less challenging champion.
Vladimir is not necessarily a champion that needs to poke. His Q gives him very high sustain for lane, the only problem is that his early game is rather weak. Thus, if you do pick Vladimir, I'd suggest practicing how to farm with his basic attacks for a bit in a custom game to ensure that you won't be stomped on in a real game. He is also very reliant on items, and if you find him more interesting, I'll teach you myself the proper items to build in certain situations.
TL;DR: Ziggs is a poke mage with somewhat difficult skillshots. Vlad is an all-in sustain mage whose job is to live through a fight while dealing heavy damage. Each works better in a different situation.
Each will work better in a certain situation. Message me if you need any help understanding their mechanics/items a bit more.