Pasta strands are long rods of pasta, which are generally round, but they are available in a square rod also. The basic difference from one variety to the next is the thickness of the strands.
Stuffed pasta consists of fresh pasta sheets that are stuffed with a filling. After the filling has been added, the pasta sheets are folded over and sealed, or another sheet is placed on top and the edges are sealed.
Soup pasta consists of pasta shapes that range in size from small to very tiny. The larger of the soup pastas are used in thicker based soups and the tiny and smaller pasta shapes are used in light or broth based soups.
Ribbon pasta, which is flat strands of pasta, is available in different lengths, widths and thickness. Some are short and wide, while others are long and narrow. Ribbon pasta can have straight or wavy edges and many varieties are available fresh and dried.
Tubular pasta is any pasta that is hollow through the center, forming a tube. They are available in many different sizes and shapes. Some tubes are long and narrow while others are short and wide.