What is the difference of RequestContext and HttpContext parameters when implementing an IHttpHandler?

Question

I am trying to implement an IRouteHandler which returns with a fully implemented IHttpHandler.

So when I implement IRouteHandler's only one method I got a RequestContext parameter.

internal class MyRouteHandler : IRouteHandler, IRequiresSessionState
{
    public IHttpHandler GetHttpHandler(RequestContext requestContext)
    {
        return new MyHandler(requestContext);
    }
}

Later when the request is coming in my IHttpHandler in the implemented ProcessRequest:

internal class MyHandler : IHttpHandler, IRequiresSessionState 
{
    private readonly RequestContext _requestContext;

    public MyHandler(RequestContext requestContext)
    {
        _requestContext = requestContext;
    }

    public void ProcessRequest(HttpContext context)
    {
        // How is this HttpContext instance differs from the RequestContext instance?
        // Do I need both?
    }
}

How is this HttpContext instance differs from the RequestContext instance? Do I need both in my case? (I do nothing else in IRouteHandler implementation. The created IHttpHandler will serve all requests.