Epigensis vs Preformation - What's the difference?

As a noun preformation is

prior formation.

epigensis

Not English

Epigensis has no English definition. It may be misspelled.

English words similar to 'epigensis':

epigenesis, episomes, epicentres, epicenters, evasions, euphuisms, epigynes, effusions, epicness, epigones, epicenes, epicanthus, epizoons, epigynous, epigeneses, epizoans, evaginates

preformation

English

Noun

(en noun)

Prior formation.

(biology, historical) The theory that organisms are fully developed in the form of an egg or seed, and just increase in size (as opposed to (epigenesis).

*1999 , (Matt Ridley), Genome , Harper Perennial 2004, p. 174:

*:Preformation , as even Aristotle spotted, merely postpones the problem, for how did the homunculus get its shape?