The difference is how you get into the garment. A cardigan opens down the front and fastens with buttons or a zip, while a pullover has no front opening at all and is put on by pulling it over your head. Remember the pullover name literally describes the action of pulling it over.
The core difference
A cardigan fastens down the front, while a pullover has no opening and is pulled over the head.
- cardigan — a knitted sweater that opens down the front and fastens with buttons or a zip: She pulled on a cardigan as the evening turned cool.
- pullover — a sweater with no front opening, put on by pulling it over the head: He wore a wool pullover on the chilly morning walk.
How to tell them apart
The names give the fastest way to remember which is which. Pullover describes exactly how the garment goes on, by pulling it over the head, while cardigan comes from a person's name rather than a description of the garment: it is named after James Brudenell, the 7th Earl of Cardigan, a British military commander of the 1800s.
Pullover has an unrelated sense in exercise too, describing a move performed lying on the back where a weight is moved from behind the head to above the chest.
