What is the difference between a static method in PHP and an instance method? Workaround

What is the difference between a static method in PHP and an instance method?
is not the difference between the use of methods, but there is no difference in performance

------Solution--------------------
It should be said that static methods are more memory-efficient than instancing.
------Solution--------------------
Static then open do not call database and server memory and CPU again
The instance you are talking about is dynamic access. That way, database functions and other reads generate the corresponding static code.
In search engine aspects are said to be static in favor of search some, but the feeling gap is not very big, can only say if is static best use static generation.
------Solution--------------------
Static faster

