A business plan for investors requires a lot more information than a plan for the bank. The decision-making process is generally more intensive as (depending on the agreement reached) the funds are handed across without a requirement to pay the money back.
The goal when preparing a business plan for investors is to provide sufficient information for them to know whether they are interested in the concept and want to know more, or they understand the concept and are not interested.
We try to limit business plans for investors to between 20 -30pages. It is important to cover off what makes your business so special, how you will commercialise and monetise your concept, who is involved in the project, the risks involved, and how the money will be spent.