As a noun homogeneity
is the state or quality of being homogeneous.
As an adjective homogenous is
(biology) having the same genetic structure; exhibiting homogeny.
homogeneity
English
Noun
(homogeneities)
The state or quality of being homogeneous.
homogenous
English
Adjective
(
en adjective)
(biology) Having the same genetic structure; exhibiting homogeny
(proscribed)
Usage notes
According to The Oxford Guide to English Usage , 'homogenous' is a frequent error for homogeneous.