In our business and engineering consultancy experience, we have often had to explain the difference between a feasibility study and a business plan.
A feasibility study is not the same thing as a business plan but it is quite understandable why they are confused. The process of writing a business plan and writing a feasibility study are very similar but the feasibility study should be completed prior to the business plan.
The feasibility study helps determine whether a business idea is a viable option or not. The feasibilty study should be focused mostly in potential competitors, financial, legal and tax constraints, and always the worst-case scenarios. If feasibilty study is negative you can save a lot of time effort and money. If the feasibility study is positive you are just one step away from a business plan, one step closer to success. The business plan should be focused mostly in the marketing and sustainable growth strategies.
What is more, we strongly recommend the order of magnitude feasibility study prior to the feasibilty study. This kind of pre-feasibility studies are very cheap and fast analysis of costs, incomes and times to a level of detail that allows a viability estimate within an order of magnitude.