a year/one year

[WilliamTaft]

Woodrow Wilson’s early life was marked by poor health and a passion for learning. His education included tutoring by Confederate soldiers, classes with his father, a year at Davidson College, a bachelor’s degree from the school now called Princeton, one year of law school, and a doctoral degree in history and political science from the University of Johns Hopkins.
Source: VOA Learning English - America's Presidents - Woodrow Wilson: Idealist

What's the difference between "a year" and "one year" in this context?

 

[Rover_KE]

None, except that 'one year of law school' emphasises the fact that a qualification in law typically takes much longer to acquire, and he could never have claimed much expertise in the subject.