Still under construction ☽◯☾ but you're welcome to look around.
Reconstructionism treats the ancient religion as interrupted - largely by Christianisation - and works to rebuild practice as historically accurately as possible from primary sources: Homeric hymns, Hesiod, Pausanias, epigraphic and archaeological evidence.
Revivalism also accepts the interruption, but takes a looser, more adaptive approach - treating Hellenismos as a living tradition free to evolve with the modern practitioner, rather than bound to strict historical accuracy.
Successionism rejects the premise of interruption altogether. Its adherents hold that some thread of practice, belief, or lineage carried the tradition forward continuously, even through the centuries of Christian dominance - making modern Hellenism a continuation rather than a revival or reconstruction.
Two words that get thrown around a lot in this space: reconstructionist and revivalist.
A reconstructionist approach treats the ancient evidence as the primary authority, rebuilding practice as closely to its original historical form as the available evidence allows.
A revivalist approach uses that same evidence as a foundation, not a fixed blueprint - historically grounded, but adapted to fit how we actually live today.
In practice, the line is blurrier than it sounds. Even the strictest reconstructionists have made practical adjustments. Animal sacrifices, for example, isn't part of modern practice for most people, regardless of where they fall on the spectrum.
Both are valid approaches in modern Hellenic Polytheism. If you're new here and still working out where you land, you don't have to decide today - or ever.
Successionist claims are a minority position within the modern Hellenic community and are generally treated with scepticism by scholars and by reconstructionist/revivalist practitioners alike, given the extensive historical evidence of suppression and discontinuity following Christianisation. That said, the position persists, sometimes tied to family oral tradition claims, sometimes to specific modern organisations asserting an unbroken lineage back to antiquity.