Maʿrifat al-Ḥaqq (maʿrifat of the Real) is to know His oneness (tawhid) as manifested to His creatures through His names and attributes.
As for ḥaqīqa (inner reality), it is to believe that it is impossible to truly know Him due to the impossibility of comprehending the attributes of samadiyya (absolute self-sufficiency) and rubūbiyya (lordship). For Allah says: "No knowledge can encompass Him"; for samad means one whose attributes and particularities cannot be comprehended.
One of the great masters has said: Maʿrifa (maʿrifa, experiential knowledge of God) is to prepare the secret (sirr, the innermost heart) to be present by reflecting on the states of ecstasy (wajd) that arise during dhikr (remembrance of God), according to the successive indications of unveiling (kashf). The meaning of this saying is: that the secret (sirr) witnesses the majesty of Allah, shows reverence for His due, and exalts His rank in a manner that words are incapable of expressing. When Junayd was asked, "What is maʿrifa?" he replied: The secret (sirr) of the servant witnesses the majesty of Allah in such a way that...