Difference between API and ABI

Question

I am new to linux system programming and I came across API and ABI while reading Linux System Programming.

Definition of API :

Answer 1

API: Application Program Interface

This is the set of public types/variables/functions that you expose from your application/library.

In C/C++ this is what you expose in the header files that you ship with the application.

ABI: Application Binary Interface

This is how the compiler builds an application.
It defines things (but is not limited to):

• How parameters are passed to functions (registers/stack).
• Who cleans parameters from the stack (caller/callee).
• Where the return value is placed for return.
• How exceptions propagate.