Wikipedia's take, which is consistent with what I've read elsewhere:
https://en.wikipedia.org/wiki/S/PDIF
S/PDIF is an audio
format, transmitted over an optical cable
or a co-axial cable. Optical fiber or copper, the
format is the same. They are both S/PDIF cables.
Your LG TV uses an optical S/PDIF output. Get the optical cable. It is also called Toslink.
It's a digital signal cable, so there may be zero performance advantage for an expensive cable. You may be just as happy with the 6' version of this one:
https://www.monoprice.com/product?c_id=102&cp_id=10229&cs_id=1022901&p_id=1447&seq=1&format=2
It's $2US.
Funny how the cheapest 6' Toslink cable that BestBuy sells is $15US. (I might cheerfully pay that, if I was in a hurry.)