The other CAD product you mentioned is a parametric history based program. Autodesk Inventor is also parametric. (Fusion is not.)
Parametric means that when you make changes to sketches, the features will follow these changes as the part is re-built after any edit. The weakness to this style of modeling is that it is easy create dependencies between features that can make editing difficult. A small change in one feature can effect many features that come after.
Fusion carries no history between sketches and features. The sketch is preserved so that you may edit it and re-model the 3D features. Another approach available in Fusion is to directly edit your sketched feature without having to edit the sketch. Commands like Tweak Face and Push-Pull can help.
Phil Eichmiller Software QA Engineer Fusion Quality Assurance Team Autodesk, Inc.