The Holy Trinity is an important subject of iconographic representation in Eastern Orthodox Christianity, and has a rather different treatment from depictions in the Western Churches. There are two different types of Holy Trinity icons: the Old Testament Trinity and the New Testament Trinity (Троица Ветхозаветная and Троица Новозаветная in Russian).
Though this is not its traditional title, this icon is sometimes called "Old Testament Trinity" because of its relationship to Genesis 18:1-15. In Genesis 18:1-15 three individuals appear to Abraham at the Oak of Mamre. The interpretation that this appearance is related to the Trinity is a Christian interpretation of the Hebrew scriptures. Consequently, the title of "Old Testament Trinity" is interpreting the Genesis narrative as much as it is naming the icon. From certain Christian theological perspectives calling this icon "Old Testament Trinity" is a form of Supersessionism.
The "New Testament Trinity" depicts the Father, the Son and the Holy Spirit distinctly, and although far more familiar from Western models, is actually of Greek origin. Christ may be shown either as an adult, (in this case he is sitting to the right of his Father) or as an infant sitting on his Father's knees, which is the norm in early Greek depictions. This type is also called the Paternity icon, and is found from the 11th century onwards, although it did not become widespread in Orthodox art until after the Fall of Constantinople, under Western influence, when an adult Christ is the norm. The Father is painted as the Ancient of Days, a white-bearded man with a very special type of nimbus (it contains two rombic figures: one is red, another is blue, or is a triangle). The Holy Spirit is shown as a white dove with a halo of the same type as Father has. The dove may be placed between the Father and the Son (if they sit near each other at the same level), or the dove may be shown in a beam of light from the mouth of the Father, as if the Holy Spirit was just sent by Him.