Reflective writing is an opportunity to express what you know and how it relates to your experience. It helps you to think about the process of learning and make it more useful to you.
It is important to be critical and not just descriptive. You should make links between actions and performance and suggest ways in which you will do things differently in the future.
Essentially, a report is a short, sharp, concise document which is written for a particular purpose and audience. It generally sets outs and analyses a situation or problem, often making recommendations for future action. It is a factual paper, and needs to be clear and well-structured.