Sashimi refers to raw slices of fresh fish arranged on their own
Sushi is generally distinct from Sashimi as it involves vinegar flavored rice.
There are various types of Sushi depending on the shape and construction these include:
Nigiri-sushi , which involves a slice of raw fish atop an oblong, compacted mound of rice. Nigiri is generally served in pairs, with a little dab of wasabi between the rice and the fish, and sometimes with a small strip of nori (seaweed) belting it all together.
Maki-sushi , which involves strips of fish and vegetable laid in rice and rolled inside nori to make a long cylinder. It's then typically served cut into 6-8 pieces.
Uramaki-sushi , which is the "inside-out" roll with fish in the center, then nori and finally the sushi rice as the outer layer. These are, like the regular maki, created as long cylinders then sliced.
Temaki-sushi , involves a nori cone which holds the fish, rice and other ingredients inside.