Definition
- Definition, with respect to a function indicates that the body of the function has been developed.
- With respect to variable, it means a value has been associated/defined with that variable.
- A function can be defined only once.
- Once a function or variable has been defined, it is ready to be used.
- A variable can be re-defined multiple times, as and when required. This depends on the language and the scopes.
- Memory is allocated when function or a variable is defined.
Declaration
- Function declaration basically means that a name has been given and the parameters have been mentioned.
- No value is associated with a variable when it is just declared.
- Its body hasn’t been developed yet.
- Once a function or variable has been declared, it is not yet ready to be used.
- A function or variable can be declared any number of times.
- Memory isn’t allocated when a function or variable is declared.
