What's the difference between somniferous and soporiferous?

Somniferous

Definition:

• (a.) Causing or inducing sleep; soporific; dormitive; as, a somniferous potion.

Example Sentences:

• (1) Introduction of free phenobarbital to such animals does not produce any somniferous effect.

Soporiferous

Definition:

• (a.) Causing sleep; somniferous; soporific.

Example Sentences: