Why do contacts I enter on my phone end up in my Outlook contacts on my computer?

I use my MacBook and iPhone for personal and business activities. On my MacBook I keep personal contacts in Apple's Contacts application. I keep my work contacts in Outlook. On my iPhone, all contacts are synchronized into the Contacts application. However, when I enter a new contact into my iPhone, that contact is synchronized into Outlook on my MacBook, whether that contact is personal or business.

Is there any way, when I enter a contact on my iPhone, to specify its destination on my MacBook?