Algorithm: An algorithm is a sequence of computational steps that transform the input to an output. It is a tool for solving  a well-specified computational problem.

Strategy: A strategy is an approach or a series of approaches that devised to solve a computational problem.

An algorithm is a strategy that always guarantees the correct answer.A strategy might yield incorrect results, but a correct algorithm will always produce correct results.Strategies are invented on the other hand algorithms are more or less tested and trusted standards Strategies are flexible, but algorithms are rigid i.e. they follow only one set of procedures.