A more detailed planning tool than the business case, the business plan is a "Set of documents prepared by a firm's management to summarize its operational and financial objectives for the near future (usually one to three years) and to show how they will be achieved."
Read more: http://www.businessdictionary.com/definition/business-plan.html#ixzz1q2z...
See the Small Business Administration's Business Plan Template: http://web.sba.gov/busplantemplate/BizPlanStart.cfm