The importer's and exporter's banks act as collecting agents in the transaction as they monitor the payment and delivery of relevant documents for the goods release.
Term means that the exporter has extended credit to the importer who may accept the documents and pay at a later date (documents against acceptance). Payment of the term acceptance is reliant on the importer's ability to pay on the due date with loss of control of the goods by the exporter.
Sight means the importer is requested to pay immediately on presentation of the collection documents (documents against payment).
While a collection offers a little more protection for the exporter, the importer's ability to choose when they pay is more limited.