The major difference I noticed between these two is that in the Agama version, after each class of being is introduced, the Buddha stops to chant a dharani for them. The dharani is rendered in romanized Chinese in the text, which means it was rendered in Siniticized Sanskrit (or probably Prakrit?) in the source manuscript.
Aside from DN32's use of what appear to be mantras, I was unaware that any Sravakayana material taught anything esoteric, but this is very explicit. Can anyone comment on the history of the DA? I know it's probably Dharmaguptaka, but do we have any earlier versions? Do we have a copy of this sutra from an extinct school's canon?
I'm curious if the DA version had dharanis inserted into it or if the DN version had dharanis removed, and if there's any way to reliably conclude one or the other. I find Thanissaro Bhikkhu's introduction in his translation curious:
T. Bhikkhu wrote:Metrical analysis indicates that the long "tribute" section of this discourse is very old, while the verses in the introductory section — which is also found in the Samyutta Nikaya — are later in form. This fits with a more subjective judgment: that the tribute was an earlier composition — in the honorific style of the ancient court bards — to which the introduction was added later.
So it sounds like the original could've very well been something like a dharani.
Either way, the DA text seems to suggest that esoteric practices were in play with the Dharmaguptaka school long before the period historians attribute to the rise of Mahayana and, most probably with other early schools as well.