The difference.
PRIVATE ADDRESSES
Used inside local networks.
Reserved ranges that are not routed on the internet.
Your devices almost certainly use them.
PUBLIC ADDRESSES
Routable on the internet.
Your router has one, provided by your connection provider.
WHAT THAT MEANS
Every device in your office appears to the internet as the same public address.
WHY THAT WORKS
Your router tracks which internal device made each request and returns responses accordingly.
WHAT IT PREVENTS
Direct connections inbound to a specific device.
WHY THAT IS USUALLY GOOD
It is a form of protection.
WHEN IT IS INCONVENIENT
When you want to run a service reachable from outside.
THAT REQUIRES
Configuration on the router, and it should be done deliberately and securely.
WHAT TO REMEMBER
A private address is meaningless outside your network.
Quoting one in a support ticket tells nobody anything.