Difference between tostring() and convert.tostring()

The basic difference them is Convert.toString(Variable) handles null values even if variable value become null but variable.toString() will not handle null values it will throw a NULL reference exception error.

Convert is always safe as compair to toString().

example :

using System;

using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks; 

namespace csharpExamples

{
   class Program
   {
      static void Main(string[] args)
      {
          string abc = "" ;
          abc = null;
          Console.Write(abc.ToString());
          Console.ReadKey();
      }
 }

And if you use Convert.ToString() . then you need to change this line of code ..

Console.Write(abc.ToString());
          to 
Console.Write(Convert.ToString(abc));