Your marketing plan is a small subsidiary of your business plan. The business plan is responsible for spelling out what your business does and does not do as well as the ultimate business goals. It is more than merely marketing as it discusses your locations, financing, staffing, and strategic alliances. It also includes your vision.
Overall, think of the business plan as the cornerstone for your business. For new marketing or business measures, you need to alter the business or marketing plan. Your business plan should encourage an environment where your marketing plan can grow, thus both should reflect well on one another.