Were there different types of milkmen?

Yes, there were different types of milkmen depending on the time period and region. In the early 20th century, there were milkmen who delivered milk from their own dairy farms. In the mid-20th century, there were larger dairy companies that employed milkmen to deliver their products. Today, there are still independent milkmen who deliver from local farms and also dairy companies that employ milkmen for delivery.