Strategy _ similar to business strategy, marketing plan will capture strategies required to support your business strategy. For example if your business goal is to achieve 20% increase in sales, your marketing strategy would be to 1) introduce new product, 2) increase price for premium offerings, 3) recruit more distributors and offer commission scheme and so on. Strategy is king. When you can see your business in totality, I can assure you that you will find it easier to manoeuvre. Marketing plan is the place to address all these issues.
When I ask entrepreneurs and small business owners, it is not unusual for not having any marketing plan. I once read that Sir Richard Branson never had any marketing plan when he started the 1st Virgin business many years ago. In fact in one study of entrepreneurship (I couldn't recall the name of the study) was that as much as 50% of entrepreneurs and business owners don't have a business plan and marketing plan when they first started the business.