In obsolete|lang=en terms the difference between period and collection
is that
period is (obsolete) a specific moment during a given process; a point, a stage while
collection is (obsolete) the act of inferring or concluding from premises or observed facts; also, that which is inferred.
As nouns the difference between period and collection
is that
period is (obsolete|medicine) the length of time for a disease to run its course while
collection is a set of items or amount of material procured or gathered together.
As an adjective period
is appropriate for a given historical era.
As an interjection period
is (chiefly|north america) and nothing else; and nothing less; used for emphasis.
As a verb period
is (obsolete|intransitive) to come to a period; to conclude.