Hi TSZ
[ I just noticed your apparition here
... welcome ... I am very interested in the psychology Tarot interface as well. I notice you are deciding about a deck ... maybe the mythical tarot would suit your focus ? ]
Anyway, to get on to your question, I see many facets here:
Magician is Mercury ; ruled by that planet and he (the Magician) is the God Mercury and the 'function' Mercurius
http://www.dominantstar.com/tmerc.htm
In his role as Psychopomp he can traverse the 3 worlds; heaven , earth and the underworld. He is also a messenger - fleet of foot carrying a message scroll, he delivers the instructions of the Gods. As a planet Mercury is closest to the Sun ( a symbol of Godhead and the divine) and can be seen as a mediator between the other planets and the Sun. In its association with Gemini - the twins; one was mortal, the other immortal; so in a way he represents our two natures - the separation , the finding and the the joining together ( both twins eventually end up in the heavens).
Mercury 'rules' the joining of heaven and earth, and the conscious with the unconscious and . perhaps, has a role in regulating the ego between the Super-ego and Id. - The 'Great Work' of marrying or 'co-joining' the Sun and the Moon
In my system ( based on a blend of the Kabbalistic Tree of Life and asto/psychology ) the basis is the Sun Moon relationship ; The Moon (unconscious) is seen as the centre of the lower triangle surrounded by the three inner and personal planets, Venus and Mars (in a polarised base line) with Mercury at the apex ; here, surrounding the Moon are the basic inner astrological forces and base drives of psychology, the primary triad.
The Moon links up with Sol through Mercury (the Tree is rooted in the socio-cultural environment via persona which provides regulating feedback to pass up the tree to the higher triad.
The higher triad is a reflection of the lower consisting of the 3 outer and transpersonal planets - Here I see Neptune (as a higher vibration and function of Venus). Its connection with the worlds below, and the link it makes with the 'mystical' for me , is more of the nature and function as depicted in the Hanged Man.
So, In a way, yes, they are similar but have IMO a different function. Perhaps we could say that the Magician regulates the forces of 'intelligence' and The Hanged Man regulates connection to the mystical or that realm of 'mind' where consciousness is non-local ?
I was trying to be brief
....
and relate mostly to Magician and Hanged Man so I only outlined the basics and left a lot of the system out.