What Is The Difference Between Spdif And Phono Whats The Difference Between Optical Audio And Coaxial Audio Connections?

Whats the difference between optical audio and coaxial audio connections? - what is the difference between spdif and phono

From what I understand it is digital, but different.

Surround Sound System have both? Here is the list of connections is, I can not find coaxial audio output on the list ...

Surround Receiver
1 x USB - front | 1 x audio line-in (mini stereo 3.5 mm) - front | 1 x headphones (mini stereo 3.5 mm) - front | 1 x HDMI output (19 pin HDMI Type A) - rear | 1 x component video output (RCA phono x 3) - rear | 1 x composite video output (RCA phono) - rear | 1 x audio line-in (RCA phono x 2) - rear | 1 x SPDIF input (TOSLINK) - rear


What is TOSLINK, too?