Adi Buddha is the original Buddha who is without beginning and without end. He is said to be infinite, self created and revealing himself in the form of blue flame coming out of lotus. In Nepal, Swayambhu is worshipped as Adi Buddha.
Vajradhara representations are almost always "Dharmakaya" blue.
Here an artist choose the relatively rare white because the artist is stressing on the widom aspect, usually depicted as the white saktis, as opposed to the skillful means aspect of the Blue Dharmakaya Buddha.
In this Adi-Buddha Statue, Crossed hands suggest Vajradhara. Mudra of this Adi Buddha is unusual. It is "an alternate form of the dharmachakra mudra".