I don't know if college is the dividing line so much as people in large institutions (hospitals, universities, government, unionized industry, the military) versus entrepreneurs, contractors, self-employed folks, people in startups, and small businesses generally.
Institutions compress the range of outcomes, pool lots of performance risk, and provide economic ballast in downturns. They tend to have high longevity. I think institutionalists are usually going to make steadily more money until they retire.
The more entrepreneurial types of employment have a broader range of outcomes, with individuals bearing more risk, and the financial ups and downs are greater. They often have more turnover. Because the range of outcomes is greater, some people will consistently be making more money throughout their careers, but others will suffer a layoff and have to take a lower paying job, or will simply get tired of working so hard and become less productive and make less as they age.
I don't think these categories track the college/no college divide neatly so much as institutionalists tend to have a college degree, although many don't.