Are you experiencing any functional issues with these iPhones, or are you examining them for academic purposes?
It's not uncommon for smartphones to display slight variations in battery percentage, and there can be several reasons for this.
Sometimes, widgets may not refresh immediately, causing a slight delay in displaying the updated information. This could explain the slight difference between the widget (80%) and the main battery indicator (79%). To ensure the widget displays the latest information, try swiping down on the widget to refresh it manually.
Try restarting your iPhone. This can often resolve minor software issues and might fix the discrepancy.
While a small difference between the battery percentage shown in the widget and the main indicator is perfectly normal, don't fret! However, if you notice significant jumps in percentage, inconsistencies that persist, or a rapid decline in overall battery health, it's wise to further troubleshoot the issue or consult a professional. This way, you can ensure your iPhone's performance remains optimal.