What are 'gazelle' and 'cheetah' startups as per Hurun?

India is currently home to 67 unicorns, 46 gazelles and 106 cheetahs as against 68 unicorns, 51 gazelles and 96 cheetahs in 2023, as per Hurun India Future Unicorn Index 2024. According to the research firm, 'gazelles' are startups that could become unicorns in the next three years. Meanwhile, 'cheetahs' are startups that may become unicorns in five years.