Is there a difference between caviar from a jar and roe served with sushi?

In the kitchen, roe from a variety of fish species is used: trout, salmon, cod, lumpus… However, caviar is made entirely of sturgeon roe.

Sushi may be made with roe from any species, including sturgeon. However, according on what I’ve observed, they’re most commonly employed as flying fish, capelin, or salmon.