What's the difference between crookback and gibbous?

Crookback

Definition:

Example Sentences:

(1) A moment when Underwood, told that he has lost the support of his party, hunched over as if to prevent his furious feelings exploding from his chest, might have come directly from Spacey’s stage performance as the crookback king.
(2) He was Richard Crookback in Shakespeare's Tudor propaganda version of the story – "that foule hunch-backt toade" (the first recorded use anywhere of the description hunch-back) – which may have portrayed him as a serial murderer, but also as passionate, highly intelligent and possessed of a dark wit.
(3) The monarch, whom Tudor historians nicknamed Crookback Dick, was killed on 22 August 1485 at the Battle of Bosworth Field by Henry VII's soldiers.

Definition:

(a.) Swelling by a regular curve or surface; protuberant; convex; as, the moon is gibbous between the half-moon and the full moon.
(a.) Hunched; hump-backed.

Example Sentences:

(1) However, as each condition is rare, the occurrence of both gibbous deformity due to Hurler's and diastematomyelia in the same child, makes it unlikely to be a chance association.
(2) Twenty-two patients with Pott's disease and symptoms of back pain, gibbous deformity, and neurological deficit underwent thoracotomy.