This is something of a companion piece to my other thread "MBTI types that best represent Jung's types". Please note that the definitions referenced here are based directly on those of Psychological Types, and do not reference the adaptations of Jung's original theory such as MBTI or Socionics. Hence why I refused to assign those types initials. Most of my research into the Enneagram is based on reading the theory on The Enneagram Institute website, not on any of the books written by Riso and Hudson. Contributions from readers of those books are appreciated.
Below is a list of Jung's types matched to Enneatypes.
Extraverted Thinking: 1w2 so/sp
Extraverted Feeling: 2w3 so/sx
Extraverted Sensation: 7w8 sx/so
Extraverted Intuition: 7w8 and 8w7 sx/so
Introverted Thinking: 5w4 sp/so
Introverted Feeling: 4w5 sx/sp
Introverted Sensation: 9w1 sp/so
Introverted Intuition: 5w4 and 9w1 sp/sx
Enneagram theory draws correlations between Extraverted Thinking and One (and Three, to some extent), Extraverted Feeling and Two, Extraverted Sensation and Seven, Introverted Thinking and Five, Introverted Feeling and Six, and Introverted Sensation and Nine. I'm not aware of any correlations made either with Jung's Intuition types or with Four or Eight. If there are, please share them.
I consider most of these comparisons to have merit, save for Introverted Feeling and Six. In my opinion, the core fears of Six do not fit well with Jung's Introverted Feeling type, at least not as a core type. That type does not desire security or support in the way Six is described. With Six, the security comes from external sources rather than one's own resources, because Six fears having to fend for itself. Introverted Feeling does have a lot of overt neuroticism, yes, but Jung believed all introverts are neurotic. Some might point to cp6s as an example of independent-mindedness in Six, but even then, that's defiance directed externally against something. Instead, I consider Four to be the most obvious match because Introverted Feeling is independent and idiosyncratic, and at times prone to bouts of melancholy, in the same way Fours are. Fours withdraw from others due to feeling vulnerable. Fours need to be authentic to themselves.
The Intuitive types required the most guesswork. Those of you familiar with Socionics associate Se with forcefulness in terms of bending the world to one's will, but between Extraverted Sensation and Extraverted Intuition, it'd be Jung's Extraverted Intuitive type which is more concerned with reshaping the world to its potential, whereas Extraverted Sensation is concerned mostly with accummulating experiences for their own sake. An Extraverted Thinking type would be too compliant to their ideals to fit Eight all that well. Thus, I think Extraverted Intuition comes closest to Eight. The Introverted Intuitive type is the most difficult of which to draw a direct correlation. I see elements of both Five and Nine (5w4 and 9w1, to be exact). Five explains the interest in exploring their psyche and desire to discover new ways of viewing things, while Nine explains the detachment of the ego and preoccupation with fantasies at expense of the external world.