Srila Rupa Goswami in his book Ujjwala Nilamani describes the five types of sakhis (cowherd girls) in Nitya Goloka Vrindavan. Here is the detailed explanation of each of them:
Sadharan Sakhi
They consider Krishna as their everything. For them, their devotion is only and only Krishna. They worship Krishna as their husband. Anything else other than Krishna holds no meaning to them.
Mirabai is a sadharan sakhi and her words "Mere to giridhar gopal dusro na koi" which means that "I am owned by Giridhar Gopal (Krishna) and there is nobody for me except Him." This clearly indicates the inner mood of Shri Meerabai.
Priya Sakhi
They love both Radharani and Krishna equally. Example, as mentioned in Ujjvala Nilami, is of Kurangaksi and Sumadhyama.
Priya Narma Sakhi
They love both Radha and Krishna but favour Srimati Radharani. Suppose if there is a sweet loving fight (mana) between the Divine Couple, the Priya Narma Sakhis will take the side of only and only Sri Radha.
However, it is seen at places that the Priya Narma Sakhis can take the side of Krishna in sweet exchanges to enhance the beauty of the lila (passtime) in a particular way to bring both Radha and Krishna together.
Prana Sakhi
*Most Imp for sincere seekers*
For Prana Sakhis, Srimati Radharani is everything. This is in the mood of Radha Snehadhika which means that they exist just for providing pleasure to Srimati Radharani. For them, nothing means anything except Sri Radha.
The book 'Demystifying The Mystical Vrindavan' is the essence and crux of this entire website.
If you are considering to dive into the final goal of our Vedic Scriptures and spiritual life, and if Radharani inspires you, do get a copy of the book .
The manjaris (or maid-servants) of Sri Radha like Ananga Manjari, Rupa Manjari, Rati Manjari, VIlas Manjari, Guna Manjari, Lavanga Manjari etc are Prana Sakhis of Srimati Radharani. They worship in Radha Dasyam bhav or serving the Lotus Feet of Sri Radha.
Chaitanya Mahaprabhu has provided the manjari bhav in the Hare Krishna Mahamantra (You can read the confidential meaning of Hare Krishna Mahamantra in context of manjari bhav and Nitya Goloka Vrindavan here).
It is to be noted that this manjari bhav is extremely confidential and not for mundane discussion but only for sincere desperate seekers who wish to completely revive their original spiritual identity. This was not possible in any of earlier yugas (Satya Yuga, Dwapar Yuga, & Treata Yuga) and Mahaprabhu has given this only in this Kali Yuga, thus it is a golden period in the entire day of Brahma to fully realise one's spiritual identity in true form.
The Prana Sakhis are nitya-siddha which means that they are eternally liberated and descend to bhuloka (earth) just to reclaim the fallen conditioned souls to topmost maha-madhurya vipralambha vraja-prema rasa or bhav in the mood of manjaris, the dear most maidservant of Sri Radha.
The Prana Sakhis do anything and everything only for the pleasure of Sri Radha and nothing for even themselves. They are younger to Radharani in age and look and act in an exact similar way as Radharani but just for Her pleasure.
Nitya Sakhi
Saints and devotees who complete their bhajan in Radha Dasyam mood and realise their swarup (spiritual form) by the mercy of Rasika Vaishnavas, manjaris and Sri Radha become nitya sakhis.
Nitya Sakhis are manjaris who serve different Prana sakhis (manjaris) as per their individual mood sprouting in their heart.
Jai Jai Shri Radhe!
Hare Krishna!
P.S. This subject is not for everybody and one needs to chant Hare Krishna Mahamantra sincerely and read these books as per their spiritual advancement to be able to understand and appreciate this subject. I have experienced the kripa (mercy) to hear these inner esoteric discussions from Rasika Vaishnavas and as directed by Sri Vrindavan Dham and hence have written this post just for my own meditation and remembrance. If you feel inspired and wish to know more about it, you must read the detailed inner meaning of Hare Krishna Mahamantra here.