Why you should work together

Usually, people live in one of two camps regarding their level of attention to detail. 

Big picture people. Give a big picture person a task, and immediately they're dreaming big. Huge. "And so in the next five years, we'll completely restructure the organization to sell ponies instead of pianos."

Detail oriented people. Ask a detail person to finish something, and two days later they'll tell you the most granular facts about every individual component. "And the steps leading down to the riverwalk on this miniature model of Chicago are all exactly .4 centimeters deep."

The best thing you can do, in writing and sometimes in life, is find your opposite, and ask these questions:

To the detail-loving writer: What's the overall point?

To the big idea writer: How will you get there from here?

It will take patience, understanding, and a enormous amount of intentional communication—but in the end, both of you will be better.