Actually isn't is sashimi? Isn't sushi the rice that goes under it?
Could be wrong though.
You're right. Sushi is a combination of sashimi slice and rice.
This is a typical sushi plate:
The red is tuna. The bottom row from left is egg (dashimaki-tamago prepared with dashi stock, sugar, etc.), prawn, squid, clam (I can't identify the type) and scallop.
Saba-zushi:
There are variations, and the image shows Bo-sabazushii and Matsumae-sabazushi. Saba-zushi is commonly a "preserve" type of sushi and is vinegary, while popular sushi dishes are served with "raw" slices.
A sashimi plate:
Three types of tuna (based on part of body), octopus, two types of shiromi (white-fleshed fish) one being bonito and the other maybe sea bream, and salmon (orange-colored), garnished with finely shredded radish and grated wasabi (Japanese horseradish).
Bon apetit!
Note: Moved thread to Japanese Food & Recipes and corrected the title.