7700 use of Definitions
Have a look at the the Identification Procedures in paragraphs 8.6.2.2, 8.6.2.3 and 8.6.2.4
I can't see mention of "postive identification" - this may well be a translation from another language into English (just look at how this is causing problems with the JAA/EASA question banks)
All three paragraphs have an option, "transfer of identifcation (see 8.6.3)". If these paragraphs do tell us how to establish "positive identification", then the transfer of identification is one of the options and therefore disproves your your explanation of the difference between the two phrases.
Additionally, once identified an aircraft doesn't need to be told he is identified again until the radar service has been terminated and the idetification process have been repeated.
If you want to reduce RTF traffic, stop telling someone who has been identified when they got airborne out of Central Europe that they are identifed every time they change frequency, until they have the radar service terminated on entering Oceanic airspace.