Heraclitus was notoriously difficult to understand even in antiquity, and we only have his direct writings in fragments quoted by others, so it's hard to say much in detail.
The key seems to have been the concept of Flux, i.e. that everything is always changing—or perhaps that change itself was the only constant—which would have been something of a departure from most pre-Socratics, who were largely concerned with determining the essential truth of reality behind the phenomena that are apparent to the eye, which was usually couched in terms of one or more fundamental elements (fire, atoms, etc.).
One explanation for Plato is that he was trying to reconcile Heraclitus's observations regarding the changing nature of phenomena with Parmenides' claim that what truly exists is unchanging, unconditioned, imperishable, etc. Therefore he posited that phenomenal reality was somehow a collection of fleeting impressions of certain Forms that exist independently of those impressions but are ultimately the models that underlie them. Later Platonists would develop that into a full-fledged emanation theory, in which the true reality radiates "down" into successive levels of differentiation and individuation until you finally get to the realm of perceptible phenomena that we inhabit, which is a reflection of the perfect unity that is the true reality.
Laozi's brand of Daoism treats the Dao as the true reality that underlies perceptible phenomena, in a way that's similar to the pre-Socratics but is a bit more explicit in its ethical implications and a bit more sophisticated in its analysis of mental concepts as responsible for the construction of perceptible reality. It's also worth noting that it's framed as a process rather than a substance. It's hard to say much more, since Laozi is a cryptic work, and modern Daoists don't necessarily regard it as foundational to their practice.
Buddhist philosophy is similar to Platonism in that it initially tried to reconcile the apparent flux of perceptible reality with the idea that something had to exist underneath it all. Abhidharma is stuck somewhere between atomism and something like Platonic Forms. Mahayana philosophy eventually abandoned the search for the ultimately real, concluding that nothing in the perceptible world could ever fit those criteria. Instead Samsara is treated like Heraclitus's Flux or Plato's Becoming, whereas Nirvana is understood as something akin to Parmenides' That-Which-Is, Plato's Being (not the Forms, but more like the neo-Platonic One, only without the emphasis on singularity), etc. The key difference is that whereas Greek philosophy and even Daoism privilege the "ultimate" reality over the perceptible, in Mahayana thought they are both equally true, mutually dependent concepts. Thus even Nirvana is a conceptual model that one must not cling to.
These Indian, Chinese, and Greek philosophies all seem to have arisen independently around the same time, with any mutual influence occurring some centuries later.
- freedom from τύφος (smoke) which signified ignorance, mindlessness, folly and conceit.
