First of all, the term "Bodhicitta" is a loaded one.
The "two types" of Bodhicitta you're speaking of, Caz, are actually Mahayana definitions--conventional Bodhicitta as compassion, altruistic intention, ,etc., and Ultimate Bodhicitta as "Emptiness/Clear Light," or however one explains the Ultimate. There's also a twofold classification in Mahayana of Aspirational, and "Actual," or Active, Bodhicitta.
But in Vajrayana, there is an additional level of meaning, where "Bodhicitta" is related to vital fluids, and the generation of Bliss, and the experience of Bliss/Emptiness. It relates to the Tigle, or Bindu, and there's lots of "partial" information out there on the Net about this, but it really should be heard from the mouth of one's teacher.
In Dzokchen, by contrast, "Bodhicitta" also relates to Tigle, but Tigle is understood in multiple ways, as well. In effect, as I understand it (not an expert by any means), Bodhicitta is the actual basis, the real condition, and as such, does not need to be "developed," as per Mahayana gradualist theory, or "Conserved" or "manipulated" as per Vajrayana theory. It can be understood in Dzokchen as the very nature of mind, which is really beyond "Mind." Experts, please correct my faulty explanation.
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