Stratagy requires the use of tactics, but tactics don't require a stratagy.
The word "stratagy" is usually reserved for a long term goal--otherwise it is pointless. Take an example from life. Let's say you have a plan for getting to work. Now, for me, that plan involves getting into my car and driving down the street. This simple plan is not complex enough or long term enough to merit the use of the word "stratagy." (It is tactics, though!) Now, if you are a student and your plan for "getting to work" involves taking a barrage of classes, passing exams, landing an intership and getting experience, networking and finding good references, researching all the possible career paths, et cetera, then this plan, once all the details are filled in, certainly counts as a stratagy. Yet still all the steps along the way are still tactics.
Hope this helps in your understanding of the term and how stratagy is used.