Hair Splitter
The making of unreasonably fine distinctions. No matter how small, the person will differentiate between subjects.
a.k.a. A ROYAL PAIN IN THE ASS.
a.k.a. A ROYAL PAIN IN THE ASS.
Person 1: "Colin just spent the past half-hour telling me the difference between magenta and pink"
Person 2: "He is such a hair splitter"
Person 2: "He is such a hair splitter"