Clause

• A clause is defined by Cambridge Dictionaries Online as being "a particular part of a written legal document." When used in legal terminology, clauses typically refer to specific sections of a document and are often numbered or indicated with headings to better separate them. Clauses are often separated to emphasize an important issue in a legal document.
  
  

Provision

• Provisions are defined by The Free Dictionary as "A statement within an agreement or a law that a particular thing must happen or be done, especially before another can happen or be done." In legal documents provisions are most often elements that are set apart from other information in the document as requirements or conditions.
  
  

Confusion

• The words clause and provision are both nouns. Because both terms essentially refer to parts of something, it is common to see the terms substituted for one another. In legal documents these two terms are often substituted for one another without specification as to the meaning intended, but they do have slightly different meanings.