Is there a difference between sino hasta and just hasta? The context is "el regreso a clases no será sino hasta 2021". I'm familiar with hasta as until, but don't think I've seen sino hasta much. Is there any difference between the two?

Is there a difference between sino hasta and just hasta? The context is “el regreso a clases no será sino hasta 2021”. I’m familiar with hasta as until, but don’t think I’ve seen sino hasta much. Is there any difference between the two?

I think what it’s saying is ”they wouldn’t be now but until next year.“. Not now, but later.