Here is the Answer,
First one is "Follow by Email (Feed Burner)"
Which is a service provided by google and email deliveries are done as I post new articles on this blog.
I do not have control over this mail deliveries and the contents it carries, It just send new post to email-id subscribed to. You can UN-subcribe to this by clicking on the mail you receive. This UN-subsciption link is provided in every mail you receive.
Second is "Subscribe to my mailing list"
When you enter your email id in this, your email id is send to me, which I add to my contact list and send you email. Don't worry I shall not give or Sell these email to any one. Nor i shall send you any Spam messages. Just News, Updates, Services in the world of XBRL. To UN-subscribe to these mail just send a blank mail with subject line as "unsubscribe " without inverted comma.
Important: Add email@example.com to your contact to receive message.