Strategy should have a solid foundation that allows you to be scalable, flexible and modular as your business grows, customers evolve and technology emerges.
In the physical world, a domain name would be your street address, your web host is your house and your website files are all the wonderful things inside your house that make it your own.
Marketing strategy is at the long-term, enterprise level. A marketing plan is the annual alignment between the strategy and tactics. Tactics execute on the predefined, measurable, monthly/quarterly milestones of the plan. They are each separate yet critically co-dependent.