This is important because it allows you to begin grouping your history into functions rather than just by employers. Because skills are transferable. Being able to type on a typewriter transfers fairly easily to keyboarding skills on a computer. Interviewing authors transfers easily to interviewing clients. Scheduling rooms transfers to scheduling workers.
Project management is project management.
You get the idea. And as you group your employment history into functions you will begin to see patterns - patterns that can help you recognize what you are good at and what you enjoy doing. Another part of your history should include specific accomplishments. As you can tell, the training function provided a LOT of capital for the other functions in the company. A prospective employer would understand that I know what to do to generate revenue - with high profitability.