Why are there symmetry differences on Ipad or Windows ? ( for sketchbook express)

Sketchbook Express and Pro are actually made by Autodesk, not Adobe.

That being said, Sketchbook Pro is a great app; I've been using it for a month or so, since Adobe took the ol' "*shrug* maybe we'll get around to it if we feel like it" line with regards to development of an Android version of Sketch.

Since this is an Adobe forum, you'd probably be better off asking over at Autodesk.