A NSL is a government order to produce something, so is a warrant. The difference is that a warrant has oversight as a check against abuse, and a NSL has removed all oversight (no judge, can't talk about it, etc).

  | The whole judicial oversight is the main and
  | most important difference

Not necessarily. If Google (or whomever) could publish all of the NSLs that they get, it would have the possibility to cause public backlash that spurns Congress into action. Let's not forget that if we use the 'secret court' (e.g. FISA) to approve these NSLs, there's a 99.9% chance of them being approved. The FISA court rarely rejects what is put to it (which makes it sort of telling that the government doesn't even want to deal with the formality of the FISA court).

  | Justice is supposed to be a balance and in
  | these case the other side is loading the scale.

You are trying to say that because you don't like National Security Letters, but you do agree with warrants that they have to contain no similarities. I disagree with NSLs, but talking about NSLs like warrants without judicial oversight doesn't require some addendum of, "OMG! NSLs ARE NOT WARRANTS! WAKE UP SHEEPLE!"