What are the differences between the strategy and command patterns in software design?

The Strategy and Command patterns solve different design problems:

• Strategy is used to select an algorithm for behavior at runtime. It defines a family of algorithms, encapsulates each one, and makes them interchangeable. For example, different sorting methods can be implemented as strategies.

• Command encapsulates a request or operation as an object, allowing clients to be parameterized with different requests, to queue operations, log, or undo them.

Main differences:

Aspect	Strategy	Command
Goal	Choose an algorithm for behavior	Encapsulate an action/request
Usage	Replace algorithms at runtime	Deferred execution, undo
Example	Different data compression methods	"Undo" button in an editor

Thus, the strategy focuses on algorithm variability, while the command focuses on managing actions as objects.