The Backup section of iExplorer is displaying the data within an iTunes backup on your computer. When you choose to Load Backup Data or Create Backup or Update Backup or Back Up Now, iExplorer creates a new iTunes backup for you. The article below explains how to avoid having this data overwritten by a new iTunes backup:
How to keep a safe backup with iExplorer
All other sections of iExplorer such as Media, Apps, Photos, Media Library, Books, and Root (with Jailbreak) are a direct connection to your iPhone or iPad and read the data directly from it without requiring an iTunes backup.