What's the difference between bitterwood and quassia?

Bitterwood

Definition:

(n.) A West Indian tree (Picraena excelsa) from the wood of which the bitter drug Jamaica quassia is obtained.

Example Sentences:

Definition:

(n.) The wood of several tropical American trees of the order Simarubeae, as Quassia amara, Picraena excelsa, and Simaruba amara. It is intensely bitter, and is used in medicine and sometimes as a substitute for hops in making beer.

Example Sentences:

(1) This study confirms earlier reports on the effectiveness of quassia tincture, which seems to be a useful alternative to clophenothane.
(2) As a result, we conclude that: a) The prophylactic and therapeutic action of the Quassia Amarga in the human pediculosis is confirmed.
(3) 454 patients were treated with quassia tincture for head lice.
(4) Crushed aqueous extracts of leaf, wood, bark and flowers of Quassia amara showed antilarval activity against C quinquefasciatus.
(5) Quassin, a mosquito larvicide isolated from Quassia amara, inhibits tyrosinase activity in the larvae of Culex quinquefasciatus.
(6) The object of this work was to find out the prophylactic action of the Quassia Amarga in the pediculosis of the human scalp.