social organisation vs social structure

social organisation and social structure both are nouns.

Word	Noun	Adjective	Verb	Adverb
social organisation	Yes	No	No	No
social structure	Yes	No	No	No

As nouns, social organisation and social structure are synonyms defined as:

social organisation and social structure: the people in a society considered as a system organized by a characteristic pattern of relationships

Other synonyms of social organisation include social organization, social system, structure.

social organisation (noun)	social structure (noun)
the people in a society considered as a system organized by a characteristic pattern of relationships	the people in a society considered as a system organized by a characteristic pattern of relationships