alleged vs supposed

alleged and supposed both are adjectives.

Word	Noun	Adjective	Verb	Adverb
alleged	No	Yes	No	No
supposed	No	Yes	No	No

As adjectives, alleged and supposed are synonyms defined as:

Other synonyms of alleged include so-called.

alleged (adjective)	supposed (adjective)
declared but not proved	required or under orders
doubtful or suspect	doubtful or suspect
	based primarily on surmise rather than adequate evidence
	mistakenly believed