Vajradharma is the primordial buddha of the wisdom (mother) classification of the highest level of Tantric Buddhism. In contrast Vajradhara is the primordial buddha of the method (father) classification of tantra.
"...in the aspect of Buddha Vajradharma with a body red in colour, one face, two hands holding a vajra and bell crossed at the heart. With the hair knotted as a crown, the two feet seated in vajra posture, youthful, sixteen years of age, adorned with silks and all the jewel and bone ornaments." (Nesar Ngawang Kunga Legpa'i Jungne, 1704-1761).
Jeff Watt 9-2020