Each of these is an approach to achieving the organization's goals at their respective strategic, tactical, and operational levels. Once the organization sets strategic, tactical, and operational goals, it should develop respective plans achieving the goals at each level.
A strategic plan focuses on the entire organization, at a high level, and establishes a formula for how the business will achieve the goals that meet the mission statement. The strategic plan might establish a target number for improving a business process.
A tactical plan describes actions (tactics) that various divisions or departments will take to meet the demands of the strategic plan. Not as high level as, and more specific than, the strategic plan, it establishes general actions and/or deadlines that support the strategic plan . The tactical plan might establish target numbers for how the divisions or departments will meet the target numbers set in the strategic plan.
An operational plan focuses on how the tactical and operational plan will actually be carried out. This should include specific numbers, deadlines, staffing decisions, and other information that details who, what, when, where, and how the division or department will do its part to achieve the organization's mission in line with the strategic and tactical plans.
Here's an example from the non-profit world:
If part of the mission is to eliminate the conditions that cause poverty, then one of the strategic goals might be to change the regulations that prevent low-income people from getting public assistance if they have any assets (such as a car or home). The strategic plan would include getting public and legislative support for such a change in federal and state policy.
A tactical goal would be to educate legislators about the adverse effect the current policies have on low-income people struggling to get out of poverty and how these policies create roadblocks that keep them in poverty (people need a car to get to their job, for example). A tactical plan that supports this would be identify which public policies are creating the roadblocks, what types of policy changes are needed, and to develop those educational materials,
The operational plan might include a series of a series of breakfast meetings with state and federal legislators. It would identify who would participate (staff, community members, which legislators,etc.), how many meetings, what pieces of legislation need to be changed or created, etc.