The difference between While and Do Whileis :
Whileloop checks the condition given with it first and if the condition is true then it enters inside the loop . That means the statements inside the loop is executed only if the condition is true.

while (true)
{
} 

Do While executes the statements inside the loop and then checks the condition , that means the code inside the loop is executed atleast once .

do
{
} while(true)

Lets check the difference with the below examples for both :
Example 1:

int i=1;
while (i<1)
{
    System.Console.WriteLine(Value of i={0}  + i);
    i++;
}
// Condition is false so no Output will be generated

Example 2:

int i=1;
do{
    System.Console.WriteLine(Value of i={0}  + i);
    i++;
} while (i<1)

// Statement inside the loop will be executed once.Hence the Output is :  Value of i=1