Regardless of how a streaming service labels them, the content remains the same. If you are looking to finish the entire series, you need to clear all 500 episodes. About 40% of these episodes are "filler," meaning they were not part of the original manga. If you want to stick strictly to the main story, you can skip those filler seasons and finish the series much faster.
The "Seasons" format for Shippuden is often misleading. Because the anime was produced weekly alongside the manga, the showrunners frequently stretched episodes with slow pacing or inserted filler seasons. For example, Season 6, 7, 9, 10, 11, 12, and 15 contain heavy amounts of non-canon filler material. naruto shippuden how many seasons