noun which may take the genitive case particle 'no'
a certain; some kind of; of sorts
Used as a prenominal modifier to indicate that something belongs to a particular but unspecified type or category. Often implies a degree of vagueness or that the thing is hard to define precisely.
彼にはある種の魅力がある。
He has a certain kind of charm.
それはある種の誤解だ。
That's a misunderstanding of sorts.
ある程度 means 'to some extent' and modifies verbs or adjectives, while ある種 modifies nouns to mean 'a certain kind of'.
Compound of ある (a certain) and 種 (kind, type).