Nidhi Svaroops of Pushti Marg

Most sects follow one or may be two forms of their Ista-Devata (main deity).  The iconic representation of their main deity is usually restricted to these forms.

For example, Ramanuja sect worships the Lord Vishnu sleeping on the great cosmic Ananta.  They accept the standing version of Vishnu as the uttsav-murti for their sleeping version of the bigger "mula-vigraha". 
Madhava sampradaya accepts the Udupi Krishna as their ideal form of Krishna. 
Gaudia sect accepts 'Rama, Sita, Lakshman, Hanuman' as one set and 'Radha, Krsna' as the other set of their official deities. 

Iconically, there is only one way to represent these deities in their own sects.

In Pushti Marg, we have a choice of seven main 'forms' / iconic representations of God. Some of the forms have different names, but their forms are similar.

ShriNathji is holding aloft the mountain.
Navneetpriyaji, BalKrishnaji, Mukundraiji are all baby forms with butter ball in one had.
Mathuradhish, Dwarikadhish and Kalyanraiji are variations of Vishnu svaroorp, with four arms and four 'aydha'.
GokulChandramaji and Madanmohanji are both flute playing versions of Krushna.
Vithhalnathji is a popular form from South India.
Gokulnathji is a flute playing Krushna with four arms.
Natavarlalji has Krushna dancing with a bowl of food in his hands.

In Pushti Marg, svaroops we worship are called 'Nidhi'.
Nidhi means an ocean or cornucopia - source of unlimited wealth, prestige, fame and status.
All svarups of the Lord are Nidhi-svarups in their own right. 

Svarups worshiped by Shri Vallabh and Gausaiji's family are known as their Nidhis.  Of the numerous svarups they gave and received in their life time, those svaups that were passed on to the seven sons of Gausaiji, are popularly called the Nav-Nidhis.

Svarups given to vaishnavs by their Guru for seva are said to be the Nidhi svaups of that particular Guru.  We should worship our sevya-svaroop as our most beloved Nidhi-svarup.  In Pushti Marg we are lucky in that our ancient gurus have given us seven different iconographic versions of Shri Krushna.  We can choose to worship the form that best suits our bhava / bhavana. 

Shri Nathji :- Lord Shri Govardhan-dharan has dark hue and is carved out of stone.  This depicts Krushna lifting mount Govardhan with his left hand and resting this right hand on his thigh.  (Nathadwara - Rajasthan)

Navnit Priyaji :- Baby Krshna has golden hue and is made from pancha-dhatu (bronze).  This form depicts a baby crawling on the floor with a butter ball in his right hand and keeping himself upright with his left hand on the floor. (Nathadwara - Rajasthan)

Mathura-Dhishji :-Lord of Mathura has dark hue, four arms, and is similar to the conventional image of Maha-Vishnu and is carved out of stone.  The stele behind the svaroop is arched. (Kota - Rajasthan)

Vitthal Nathji :- Lord and his beloved are of silver or pale gold (difficult to say due to size and viewing distance).  This tiny couple stand with their hands on their hips. (Nathadwara - Rajasthan)

Dwaraka-Dhishji :- Lord of Dwarak is of dark hue and made of stone.  Like Mathura-Dhishnji, the iconography of Dwarikadhishni is similar to that of four-armed Lord Vishnu.  Dwarikadhish's stele is straight / squared at the top.  (Kakaroli - Rajasthan)

Gokul Nathji :- Lord of Gokul is of golden hue and made of bronze.  There are two gopies who flank this small image of the Lord.  With two arms, the Lord is playing the flute, one arm lifting the mountain and with one arm blessing his devotees.  (Gokul - UP)

Gokul Chandramaji :- The "moon" of Gokul is a dark wooden image of the Lord playing a flute. (Kamvan - UP)

Maadan mohanji :- Golden hued metal icon (pancha-dhatu) of the Lord is playing his flute with two gopies on either side of him during the Rasa-uttsava. (Kamvan - UP)

Bal-Krshnaji :- Baby Krshna is dark hued and like NavneetPriyaji has a butter ball in his right hand. (Surat - Gujarat)

Natavarlaji, Mukundraiji and Kalyanraiji, though not set up as Nidhies, are worshipped as smaller nidhis.