What is the difference between Single, Twin, Quad, and Octo LNBFs?
The difference is the number of independent outputs, which sets how many separate receivers (or tuners) can be connected directly. A Single LNBF has 1 output (1 receiver), a Twin has 2, a Quad has 4, and an Octo has 8. Each output independently supplies its own polarization and band selection, so every connected tuner can watch or record any channel independently.
The key point is that a Quad LNBF is not the same as a Quattro LNBF. A Quad has four fully independent outputs that each respond to the receiver's 13/18V and 22 kHz commands, so it directly feeds up to four receivers without a multiswitch. A Quattro LNBF instead outputs the four fixed sub-bands (low/high band x vertical/horizontal) and must feed a multiswitch, which then distributes to many receivers.
Choose the output count based on how many independent tuners you need to feed directly. For a home with a single PVR that records two channels at once, a Twin is sufficient; for four rooms or a four-tuner receiver, a Quad; and for larger setups, an Octo or a Quattro-plus-multiswitch architecture scales further.