I'm quite new to Bioinformatics. I recently started familiarizing myself with the Human Microbiome Project Data Portal. In the portal,there are samples and files listed under data. What is the difference between samples and files? what does an individual file and an individual sample consist of?

There is usually a huge difference in the number of files and samples available (eg: for a particular body site). What is causing this huge difference?

Can someone please help me clarify.