I want to turn back to this post----to Deleuze's concept of difference as difference in itself and his conception of difference as the ground of being.

The new concept of difference relies upon other concepts such as those of multiplicity and virtuality and this gives us a conception of things as the expression of virtual multiplicities.

A question. Does Deleuze simply posit a world of pure difference in which unities are explained as secondary phenomena?

Virtual multiplicities are structures in the sense that these are composed of purely formal elements defined by the reciprocal relations between their component elements. Hence we have a system of multiple non-localised connections between differential elements that are embodied in relations and terms. In Diifference and Repetition Deleuze says:

The reality of the virtual consists of the differential elements and relations along with the singular points which correspond to them. The reality of the virtual is structure. We must avoid giving the elements and relations which form a structure an actuality which they do not have, and withdrawing from them a reality which they have. (p. 209)