Both stuffed shells and manicotti are Italian stuffed pasta dishes made by par-boiling the shells, stuffing them with a ricotta-based filling (usually with mozzarella and Parmesan and sometimes spinach and meat), lining in a baking dish, covering with marinara and cheese, then baking. The difference between these two favorite stuffed pastas lies primarily in the pasta itself. Stuffed shells: made with conchiglioni pasta, the larger version of conchiglie, which means “conch shells.” The jumbo shells open up like a shell and hold the stuffing equal to the size of an egg.  The shells are easy to stuff by adding the filling with a spoon or a piping bag.   Manicotti:  are large tubes of pasta, about 4 inches long and 1 inch in diameter. Manicotti can be smooth or have wide, thick ridges.  They hold more filling than stuffed shells which means a higher filling to shell ratio.  The long tubular shape of manicotti also makes them more difficult to stuff. The easiest to way to stuff manicotti is to pipe the filling into one end, rotate the tube 180 degrees then pipe the filling into the opposite end.