Symmetrical Communication 

Symmetrical Communication Links are just as they sound. They have the same download and Upload rates. For example, a 500/500 Mbps fiber Internet link offers download and upload speeds of 500 Mbps.

Asymmetrical Communication 

Asymmetrical Communication links, on the other hand, do not have the same download/upload rates. For example, 25/3 denotes a download speed of 25 Mbps and an upload speed of 3 Mbps. Asymmetrical data communication can make more efficient use of bandwidth than symmetrical data flows, since generally, most users will download more data than they upload