This phrase often implies a significant gap with emotional emphasis, suggesting deep differences. Even though they grew up together, their interests in music are worlds apart.
Pro Tip 2/3
Non-literal Use
It's usually metaphorical, not about physical space, but about differences in views, tastes, or experiences. As vegetarians and meat-lovers, their food preferences are worlds apart.
Pro Tip 3/3
Cultural Expressions
Can be used to express that customs or traditions are vastly different. Celebrating New Year in their countries is worlds apart.