A sweater is a knitted garment usually made of wool, although it can be made of other materials as well. It is typically thicker and heavier than a sweatshirt and is designed to provide warmth. Sweaters come in various styles, such as pullovers or cardigans, and can have different necklines like crew necks or V-necks.
On the other hand, a sweatshirt is a loose-fitting garment made of a soft and often fleecy fabric, such as cotton. It is lighter than a sweater and is commonly associated with casual or athletic wear. Sweatshirts often have a hood and a front pocket, although not all sweatshirts have these features. They are designed for comfort and are commonly worn during physical activities or for a relaxed, casual look.