It has been so long since I used X4 I don't think I could remember what the differences are. I am usually on the newest version within a couple weeks of its release. Trying to think I will state some things I think must be new since them, but memory might fail.
Improves Transform on Duplication
Better Mesh Tool
Interactive Drop Shadow Tool
Interactive Contour Tool
Interactive Transparency Tool
More Import Formats
Better Font Support Including Ligatures
Object Hinting
Pixel View
64 Bit
Photoshop Plugin Support
Dynamic Alignment Guides
Improved Sylus Support
Live Sketch
Gaussian Blur on Drop Shadows
New Font Manager
New Ways to Slice Paths, Copy/Paste Path Sections, Enhanced Knife
New Perspective and Perspective Correction Tools
Block Shadow Tool
Symmetry Drawing Mode
I don't know which version some of this stuff entered, but THINK it is all new since X4. X4 is wayyyyyy removed from Draw 2018. You will have to move up at some point as Windows will pass you by. Maybe you don't have to climb all the way up to 2018, but why not?