"It's up to you" = It's your choice. You are free to choose whatever you wish. "It depends on you" = What is chosen depends on what you want. It's an "if... then..." situation. EXAMPLE: Employer: You're in serious trouble for what you did. Employee: I'm sorry. What happens next? Employer: It depends on you. If you want to continue working here, then you'll need to issue an apology. If you'd rather leave, then we'll need to get your forwarding address, in case we need to contact you again about what happened. In other words, the person "being depended on" is not making the decision themselves, but just providing information that allows the decision to be made. However, it's not uncommon to use "it depends on you" interchangeably with "it's up to you." EXAMPLE: Wife: What's for dinner? Husband: It depends on you. Wife: I feel like having Chinese. Husband: Okay! We'll go out to eat Chinese!