The sky is the region in which sunlight is scattered in the Earth's atmosphere, making it visible from the surface of the planet, while space is everything beyond that. The sky also includes all objects as far as we can see outside of the Earth. For example, Mars is far away but we consider it in our night sky.
https://www.linkedin.com/pulse/difference-between-sky-space-universe-onkar-singh-shekhawat
I hope this helps answer your question. Let me know if you need anything else. Good luck on your learning journey and have a wonderful day/night!! :)
