Analog Audio (RCA)
RCA audio interconnects are very common and seen on most consumer audio/video electronics. The RCA interconnect carries analog audio for only a single channel. This single channel limitation is why it is common to see dual RCA interconnects for left and right channels. The single channel limitation is also why RCA interconnects are not used for surround sound since an interconnect per channel would be required.
The point-1 in 5.1 or 7.1 surround sound incorporates the subwoofer signal. Subwoffers use the common RCA interconnect to pass their low frequency bass sounds. The RCA interconnect is perfect for subwoofers since RCA interconnects can only carry a single channel.
Coaxial (F-Connector, RF Coax)
A coaxial interconnect will give you very low audio quality. It can only provided mono (a single audio signal for left and right speakers) sound with no ability to provide stereo (separate audio signals for left and right speakers) sound. It also transmits an analog signal, which is susceptible to EMI noise and interference. However, a coaxial interconnect does also provide video, making it ideal for systems such as security cameras. See this link for more information on coaxial’s video capabilities.
BNC is a versatile interconnect that can be used to carry video, audio, and data signals. A BNC interconnect is almost always found using a coax cable, which means it can only carry a single channel. The single channel can be an analog or digital audio signal. However, it is uncommon to see digital audio signals go through a BNC interconnect.