As nouns the difference between oca and oct

is that oca is a Peruvian name for certain species of Oxalis (species: Oxalis crenata, and species: Oxalis tuberosa) which bear edible tubers while oct is form of A short form|octal|lang=en.

As a proper noun Oct is

an alternative spelling of Oct.|lang=en.

As an initialism OCT is

initialism of lang=en an optical signal acquisition and processing method that captures high-resolution, three-dimensional images from biological tissues.