What makes the difference between live weight and dead weight?

I think that the weight of something rigid is more easily carried because its center of gravity is fixed.

Being dead. haha
Dead weight lacks motion and energy/synergy. It is a denser weight.

The weight does not change. It is the fact that a dead or otherwise limp being is floppy, and will squeeze out through any available space.

The claws are extended with live weight, which keeps the lifter wiling to be very pro-active.

^^^ Example #1 yes.

When I was a teenager, my very gentle and loving cat was hit by a car. The emergency vet couldn’t save her, so we put her down. We brought her home to bury her in the yard. This was when I experienced “dead weight”. A live creature with muscle tone has synergy, as @syz says, but I can’t honestly say that I understand the physics behind it, though.

Found it.

I agree with @Bill1939 about a rigid body having a fixed center of gravity. A limp body is like a big sack of potatoes – it has be supported over a large area so as not to sag & drag. A stiff body can be supported at just a few points, so is much easier to carry. Also a live person (or your cat) can subtly shift their weight to improve the carrier’s balance & grip.

I think @Bill1939 and @gasman have it nailed. Ever notice that when a male ballet dancer lifts a ballerina, she straightens up as stiff as can be, so that he can carry her more easily? Same principle.

Im a volunteer fire fighter so i know what dead weight feels like. In a person when they are conscious and willing they help you and center themselves so they can help balance themselves in your arms. If they are unwilling and still conscious the only way it would really be hard is if they were to hit you or if they would switch the weight from front to back or side to side since it throws you off balance. As dead weight the weight is spread thoughout the body and the center of gravity is gone.