A sweater vest (known as a tank top, sleeveless sweater or sleeveless pullover in the UK) is an item of knitwear that is similar to a sweater, but without sleeves, usually with a low-cut neckline.
A pullover vest (known as a tank top, sleeveless sweater or sleeveless pullover in the UK) is an item of knitwear that resembles a sweater but lacks sleeves, typically featuring a low-cut neckline.