When chossing side or rear there is a lot that goes into it. It's best to have a Certified Mobility consultant do a needs analysis.
But here is a Closer look.
The side-entry wheelchair accessible vehicle has a lowered-floor conversion, allowing for more headspace for comfortably fitting a passenger in a wheelchair into the vehicle. Side-entry vehicles typically have removable front seats, allowing the wheelchair user to ride in the front passenger spot or actually drive the van. They can house both foldout ramps and lifts or the infloor ramp, and a center cut conversion is available for the side-entry as well.
The rear-entry wheelchair accessible vehicle features a foldout ramp power or manual and has a lowered center cut area for the wheelchair. This offers more interior space, allowing for bigger wheelchairs to fit. However, the wheelchair cannot get to the front seat position. The person in the wheelchair would be able to drive or seat in the passenger position with a B&D Transfer seat.