Witness versus Bondsman

Do you know the legal difference between a witness to a document and a bondsman? There is a legal difference and it impacts how you should interpret the potential relationships among the people on the document. A witness is testifying that he saw the person sign the document. A bondsman is creating a potential legal or financial obligation if the person for whom he signs the bond does not act as he is supposed or was not legally able to get married (in the case of a marriage bond).