"The House of Representatives distinguishes between 'privileged business' and 'questions of privilege.' 'Privileged business' relates to the order or priority of business before the House and is defined in House rules and precedents as business that has precedence over the regular order of business and so may supersede or interrupt other matters that might be called up or pending before the House. 'Questions of privilege' constitute one form of privileged business. Clause 1 of House Rule IX recognizes two kinds of questions of privilege: questions of the privileges of the House and questions of personal privilege."
CRS Report for Congress, 98-411
Federation of American Scientists: http://www.fas.org/sgp/crs/index.html