The easiest way to decide which size a daffodil is, is to bend a petal alongside the cup and compare the length of one to the other
Trumpet
One flower per stem; the trumpet as long as or longer than the perianth segments (petals)
Large Cup
One flower per stem, the cup is more than one-third but less than equal to the length of the perianth segments (petals)
Small Cup
One flower per stem, the cup is not more than
One-third the length of the perianth segments (petals)
Doubles
One or more flowers to a stem