Simple answer: Virtual reality on its own isn't a 4D experience, it's mostly 3D in terms of the visual experience on the XYZ axis. VR Users can deeply immerse themselves in the virtual digital environment with a VR headset, and the headset allows you to look around as if you have been teleported there with real-time spatial tracking.
The major difference between 4D and VR is just one dimension apart in order to achieve active presence in VR, and that is sensory experience such as vibration, temperature, wind, touch, and many more things VR in 3D can't provide.
What Can 4D VR Experience Provide?
4D VR experiences will provide the user the ability to interact with 4th-dimensional objects, but that's too complicated to explain. In layman's terms, 4D is about adding the sensory experience in VR, and mixed reality will bring 4D VR experience closer to reality.
We can also visualize tesseract geometries in VR to gain better understanding of the 4D world, but to the extent most consumer users find relevant is sensory experiences such as haptics feedback.
Currently the best thing a consumer can experience is the haptics strap or haptics suit, so the user in VR flight simulation can sense vibration, and it's very immersive for gaming and simulation training.
Check one out here
Extra Information On 3D and 4D
Take a higher dimensional object into a lower-dimensional space.
1. All this means is a perspective projection, isomorphic projection, or orthographic projection on a 2D plane. You will see this mostly on technical drawings like this:
2. Better understanding on tesseract hypercube visualization. 3D to 4D is about every dimension adds 2 sides of the lower dimension.
3. Insane data collection in VR to pack extra information to encode it into 3D spaces such as tracing the trajectory of a physically object flying through space exerted by gravity and other forces.