Individuals who cultivate in their mind-stream aspirations and practice for universal enlightenment are followers of the Great Vehicle (Mahayana). Individuals who cultivate in their mind-stream aspirations and practice for personal liberation are followers of the Lesser Vehicle (Hinayana). If they do not cultivate any aspiration or practice, then whatever scriptures they read or schools they claim to follow, they are neither Mahayana nor Hinayana.
There are individuals who adhere to Mahayana doctrines but actually practice the Hinayana path. There are also individuals who adhere to Hinayana doctrines but actually practice the Mahayana path. There are individuals who adhere to and practice Mahayana doctrines, and those who adhere to and practice Hinayana doctrines. Many more hold doctrines but do not actually practice a path.