Good question.
Pip wrote, in reply,
'The version that is most used, the one you first descibed, is the oldest version of the tree'
Which is true, to a point. The older form of the tree that Pip mentions, also has the other three sefirot of the central pillar in different places. Tiferet is, in that version, often placed in the large space that the Lurianic tree has below keter (the one that sometimes is filled with Da'at). Yesod is in the Tiferet position and Malkhut is in the Yesod position. This is a very interesting diagram as it make the tree truely symetrical on both axis.
The tree that Pip mentions as being the Safed tree is, to my mind, more the Lurianic Tree as I believe it supports two major ideas regarding the tree.
The first is that Hod and Netzach, at the base of the two pillars, are points of prophecy (as also evidenced by the usual correspondance of Moses and Aaron to these two sefirot). As such, philosophically, it is important for one to spiritually 'rise' from Malkhut to Yesod before going any further along the path of prophecy. To my way of thinking, this makes more sense than the earlier tree which permits one to 'move' from Malkhut directly to a prophecy point. I prefer to see Yesod as the true foundation of all and only from there can one appreciate and comprehend anything on a higher level.
The Lurianic tree also, I hold, corresponds brilliantly to Luria's concept of the Shattering of the Vessels, in which all things are one level 'lower' spiritually than intended.
Rabbi David Honigsberg
http://www.sff.net/people/d.honigsberg/rabbi
