Is the equanimty of the four Immeasurables different from the equanimty born from samadhi cultivation?
The four immeasurables are practices for cultivating samādhi and equanimity is both a developmental practice (samādhibhāvanā) and a mental quality (caitasika). Practicing the former leads to the latter.
I havent practiced equanimty meditation yet but it seems that the focus is different from the one born in samatha. What i mean is that the equanimty from samadhi cultivation seems more related to a non grasping/non pulling back "attitude" to what ever arises from inner expirience while the equanimity from the four immeasurables its more related to the inparciality(i dont know if this word exists =P) to all beings, understanding that we are all equal.
Equanimity is equally equanimous
with regard to all objects, is it not?