The Global 5 is based on the five core personality elements (Big Five) which have been empirically found in multiple cultures by multiple researchers when statistically analyzing peer and self rated personality trait inventories.
The Global 5 elements are Extroversion, Emotional Stability, Orderliness, Accommodation, and Intellect.The various Jung systems (MBTI, Socionics, Kiersey, etc.) come closest in usefulness to the Global5 (compared to other systems), but only contain four elements. They say close to nothing about the Emotional Stability (i.e. Neuroticism) element.
At least two of the four elements (Thinking/Feeling, Intuitive/Sensing) are not sufficiently unidimensional. For example, T/F covers aspects of Accommodation, Intellect, and Emotional Stability and N/S covers aspects of Intellect and Orderliness. This means a T could be an objective thinker, a selfish jerk, a stoic, or some combo of the three; there is no way to discern from the results.
The Jung systems also pretend/infer that everyone fits into 16 types (most personality systems share this 'everyone fits one of our boxes' delusion). With five personality elements and high, medium, low scores the least amount of boxes you can fit all people into with only general accuracy is 256.
Despite the issues, T/F correlates mostly with Accommodation and N/S correlates mostly with Intellect (source). E/I correlates very strongly with Big Five Extroversion and J/P correlates very strongly with Big Five Orderliness. So what you have with the Myers-Briggs system is basically a not so perfect Big Five minus Emotional Stability. That's why it's pretty easy to predict someone's MBTI type from their results on most any Big Five test.
I'm of the opinion that most MBTI theories (functions, type dynamics) tend to be pretty baseless and questionable. But if any of them are true, they would be true in the Big Five personality architecture since the MBTI is basically just a primitive version of the Big Five.
Is there any good reason to keep using the Myers Briggs system?
It's omission of Emotional Stability does make it a more palatable system in certain situations. Nobody's going to enjoy being branded as emotionally unstable at the corporate training camp or by their guidance counselor. However, a Big Five based system minus the Emotional Stability trait would still be better in those situations.
Since the MBTI has been pitched/sold to the general public a lot longer than any Big Five system there is a lot of material which might still have some value. A similar argument can be made for the Enneagram system. As a working personality model however, the MBTI has only one chance at survival, retool all tests so that T/F and N/S are unidimensional (like E/I and J/S already are) and market itself as a Big Five based test which does not measure Emotional Stability (for practical reasons, not as a result of ignorance).