Difference between normal dispose method and IDisposable in C# .Net

Hi, Can any one kindly explain me what is the difference between normal dispose method and IDisposable's Dispose method. Normally we use Dispose method to free UnManaged resources, and we shoud have to use IDisposable for that purpose. But in one of my project, I used dipose method for StreamWriter Object and Connection object, without using IDisposable interface. So I would like to know what is the differe nce between these 2 methods. Thanks in advance.