wiki says,
tactics:-Combinations, traps, and threats. Play characterized by short-term attacks, requiring calculation by the players, as distinguished from positional play.[319]
strategy : -The basis of a player's moves. The evaluation of positions and ways to achieve goals. Strategy is often contrasted with tactics, which are the calculations of more immediate plans and combinations
I spent a lot of time with browsing internet and finding more accurate definition for tactic and strategies but I saw there are some douts in wiki answers.