Real Time Clock vs DateTime

I have a Gadtereer FEZ Spider. I have what I sense to be a very naive question, but I cannot find an explanation. I synchronized the DateTime with the Internet. When I display the DateTime it is correct, but the GHI [b]Real Time Clock /b shows a dfferent time e.g., 01/01/1977 01:01:01. I assumed they both referred to the same internal clock and they could be used interchangeably. What is the difference between the two? When do you use one vs the other?
Thanks, Bob

RealTimeClock is a piece of hardware that lives inside your board. Its job is to run off a battery and keep track of time when power is off to the main system.

First set the RTC to internet time, then set the system DateTime from the RTC. As long as the RTC has battery power, you’re good through power cycles.

Note that you need to synchronize the system DateTime from the RTC each time your system boots. The system loses the date/time when it reboots, the RTC doesn’t.

Thank you for your help. It is helpful to know that that DateTime and GHI RealTimeClock (battery backup) are two differenct internal clocks. I have modified the application to always sync to the interent on startup as well as sync the two clocks. Should the interent not be available at startup the application sets DateTime with the RealTimeClock if it’s time is still valid. It all worked! Thank you for the clarifiaction on the clocks.