Disney bought Fox which owned the company "India Star" which had a streaming platform "Hotstar."
Disney kept local Indian content on Hotstar and added Disney content to it.
Disney then created an international alternative to Hulu (minus the Live broadcast) for the rest of the world and called it "Star" to mimic "Hotstar."
In South America, Star is not a hub in Disney+, but a separate streamer called "Star+" -- which is often bundled with D+.
So, tl:dr, Hotstar and Star are separate streamers with overlapping content.