@faraiwe @ai6yr
"The mechanical difference between four-wheel-drive and all-wheel-drive comes down to whether the driver has the ability to lock both front and rear axles so they can both receive power simultaneously"
I had a old school part time 4 wheel drive. Lock the front hubs in when off road.
Ladder frame, bash plates, clearance, approach/departure angles, high/ low transfer case, but no locking diffs. A front and back wheel spinning would stop momentum, but didn't really happen. Very capable, yet fails the above definition.
Lots of other 4 wheel drives, also didn't have such locks.
While modern systems basically use your abs brakes to direct power and stop spinning wheels. Same as a locking diff, but external. So fit the above definition. Yet lack all the other stuff needed.
I tried pointing this out to my sister, when she purchased her Subaru Outback, but she won't listen. Then her Ex drove it through a long muddy puddle.
Hers the front spoiler acted as a dam, raised the water level in front of it. Then all the muddy water went into the low air intake, at the front of it.
Needed to be pulled to nearest road for a tow truck. Then engine cleaned and rebuilt.