I am not from England but I believe that "jumper" is the British name for sweater. Sweaters in the US are usually a knitted material. They can be worn over other clothing or by themselves. When I asked google translate it said پلوور this was the Persian translation of sweater and gave some images. But the basic difference is as Sweatshirts are considered casual wear. Sweaters can be more situations and Jumpers are the British version

Jumper: US : a type of dress that has no sleeves and that is usually worn with a blouse — called also pinafore https://www.learnersdictionary.com/definition/jumper

Other people have told you what a sweatshirt is. Jumper and sweater is the same thing. Jumper is British English, sweater is American. That's the only difference.

1st one is a sweater and the 2nd a sweatshirt

sweatshirt = shirt with long sleeves for exercise sweater = a nice shirt with long sleeves, usually knitted, worn in winter months when the weather is colder. jumper = this is a British word, so I am not sure, but maybe a person from England will answer.