Leisure refers to the relationship between oneself and spare time. The question behind leisure is how to spend your spare time for yourself. In such spare time, an individual is free; in other words, one has enough autonomy to allot the time.
Therefore, there are no standards on how to allot, because it’s totally determined by oneself. What matters is the outcome. If such an outcome brings a positive experience, narrowly, it indicates self-contentment, then it’s a leisure activity; if not, it’s an entertainment.
To some extent, in the modern world that amplifies the personal diligence and effectiveness, leisure is useless, for its outcome is invisible, and easily blurred with entertainment, or even worse, blamed as lazy; it‘s generally not advocated.
Leisure, in 19th-century Paris, had a romantic name, flâneur, a word made well-known by Charles Baudelaire, as a lifestyle against industrialization.
Maybe that’s a post-acient romanticism. Nowadays, romance is extinct. People are often obedient to wealth, success, and effectiveness, which makes the world dull. Even though those who are not in the mainstream also accept such a pursuit.