On paper, a glider and a regular armchair aren't so different — both have a seat, a back, and armrests. The difference shows up at two in the morning, when a gentle, steady rocking motion can settle a baby far faster than sitting still ever could.
The motion itself is the biggest advantage. A glider moves in a smooth, level line rather than the tipping, uneven rock of a chair on curved rockers. That steadiness matters when you're holding something as precious — and as easily startled — as a newborn.
Support is the other piece. A good glider is built with a slightly higher back and wider armrests than a standard armchair, so you can support a baby's head and your own arm for long feeds without your shoulders and back paying for it the next day.
And unlike most nursery-specific furniture, a well-made glider doesn't have to leave the room once the baby grows. Add it to a living room or a reading corner, and it just becomes a comfortable chair — one that happens to rock.