ReadOnly Vs Const Keyword

READONLY KEYWORD
CONST KEYWORD
Read-only is used only when we want to assign the value at run time. Constant variables are declared and initialized at compile time. The value can't be changed afterward. 
In C#, readonly fields can be created using readonly keyword In C#, constant fields are created using const keyword.
ReadOnly is a runtime constant. Const is a compile time constant.
The value of readonly field can be changed. The value of the const field can not be changed.
It cannot be declared inside the method. It can be declared inside the method.
In readonly fields, we can assign values in declaration and in the contructor part. In const fields, we can only assign values in declaration part.
It can be used with static modifiers. It cannot be used with static modifiers.