ज्ञात्रादिकल्पनाभावान्मतोऽयं निर्विकल्पकः ।वृत्तेः सद्भावबाधाभ्यामुभयोर्भेद इष्यते ॥ ८२६ ॥
In plain words
Because all fabrications of a knower and known are absent, this is regarded as nirvikalpa samadhi. The distinction between the two samadhis is established by whether mental modifications are present or sublated.
Close to the Sanskrit
Due to the absence of the imagination of the knower and others, this is considered nirvikalpa; the difference between both is desired through the presence and sublation of the mental modification.