common seal and rubber chop

Common seal is used for a legal document. Its usage is governed by the Articles of Association of the company. Whenever a document has to be affixed with the company's common seal, a meeting of the board of directors must be held. The document has to be tabled in the meeting for consideration and approval. If approved, a director or directors will be authorized by the Board of Directors to sign on the document and then the common seal be affixed thereto, e.g. Purchase and Sale of Property, Tenancy Agreement etc.
Rubber chop is normally used in the ordinary course of business, a day-to-day usage e.g. in Sales Invoice etc.