The terms "alone" and "all alone" are related, but they have slightly different meanings:
Alone: "Alone" simply means being by oneself, without the company of others. It refers to a state of solitude or being unaccompanied. For example, if someone says, "I prefer to spend my weekends alone," it means they like to be by themselves without the presence of others.
All Alone: "All alone" emphasizes a stronger sense of being completely isolated or without any companionship. It intensifies the feeling of solitude. When someone says, "I felt all alone in the big city," it implies that they felt utterly isolated and unsupported, without any friends or family around.
In summary, "alone" indicates being by oneself, while "all alone" adds an extra emphasis on the complete absence of company, accentuating a deeper sense of loneliness or seclusion.