Message and messenger.

The same Message of Truth is delivered by different messengers. When the messenger becomes one with the Message of Truth, that is Guru. In the case of a guide, there is knowledge of the Truth of the Message, but there may still be vAsanas that need to expire before that embodiment becomes one with the Truth. But a real Guru is the living embodiment of the Truth: SrI Adi ShankarAcArya, SrI RAmakRShNa and BhagavAn SrI RamaNa MahaRShi.