Story Planner is a focused, flexible app to outline all kind of stories. Used by writers, screenwriters, producers, directors and all kind of story tellers, Story Planner has quick and easy-to-use story organization, with sync on all your devices and export options to help you...
















































































I'd say Story Wiki has a lot more customization options and is more aimed at wiki features. It has wiki-links, properties, relations and such.
But Fortelling is a good app for planning and writing your story on the go. It works offline, it connects to your google account, you can use it on your desktop's browser (subscription required)...
They're similar. I like Story Wiki for having a lot of detailed templates and I like Fortelling for its user-friendliness and portability.