Sushi is a kind of traditional Japanese food made by cooked vinegared rice, raw fish or other seafood. There are a lot of variations depend on their ingredients and forms.[1]
But vinegared rice is indispensable because this is the main difference between Sashimi and Sushi.
sushi 
sashimi
[1]Sand, J., 2015. How Tokyo invented sushi. Food and the city: Histories of culture and cultivation, pp.223-48.
sushi 