believable vs credible

believable and credible both are adjectives.

Word	Noun	Adjective	Verb	Adverb
believable	No	Yes	No	No
credible	No	Yes	No	No

As adjectives, believable and credible are synonyms defined as:

believable (adjective)	credible (adjective)
capable of being believed	capable of being believed
	appearing to merit belief or acceptance
	(a common but incorrect usage where `credulous' would be appropriate) credulous