Strategy is the thinking aspect of planning a change, organizing something, or planning a war. Strategy lays out the goals that need to be accomplished and the ideas for achieving those goals. Strategy can be complex multi-layered plans for accomplishing objectives and may give consideration to tactics.
Tactics refer specifically to action. In the strategy phase of a plan, the thinkers decide how to achieve their goals. In other words, they think about how people will act, i.e., tactics. They decide on what tactics will be employed to fulfill the strategy.