1, different values: constant value is a fixed value, while constant is an identifier, representing a fixed value.

2. Different usage methods: Constant values are usually used directly in code, while constants need to be defined before use.

3. Variability is different: the constant value remains unchanged during the whole calculation process, while the constant value will not change during the execution of the program, but it can be re-assigned in the program.

4. Different readability: constant values usually represent a numerical value intuitively, while constants can represent a value with a meaningful identifier, which increases the readability of the code.

5. Different extensibility: Constant values can usually only represent a specific value, while constants can represent an abstract concept, which can be extended and modified in the program.