In obsolete|lang=en terms the difference between bulk and collection
is that
bulk is (obsolete) the body 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 bulk and collection
is that
bulk is size, mass or volume while
collection is a set of items or amount of material procured or gathered together.
As an adjective bulk
is being large in size, mass or volume (of goods, etc).
As a verb bulk
is to appear or seem to be, as to bulk or extent.