There is some overlap in how they can be used, but there are also some unique features to both:
- Critical sections cannot be used across processes, whereas events can.
- A single manual-reset event can be used to release multiple threads at once. A critical section cannot.
- Events are compatible with
WaitForSingleObject()
et al, whereas critical sections aren't. - A thread can wait on multiple events with
WaitForMultipleObjects[Ex]()
, but it can only wait for a single critical section (using a different API).
and so on.
They are not really in direct competition; it's best to think of them as being complementary to each other.
Mutexes are somewhere in the middle. For further discussion, see What is the difference between mutex and critical section?