Since both manga are by Hanamori you can really see how simular they are even though the storyline is very different.
The characters and drawing are magnificent as you'd expect from Hanamori. The cute romantic scenes between Luchia & Kaitou (Pichi Pichi Pitch) and Yume and ? are very simular if not the same.
If you like some romance with a slice of magic, pick one or the other and you won't be disappointed.
(In my opinion Pichi Pichi Pitch is better when you watch it as an anime.)