What is the difference between an LNB and an LNBF?
An LNB is the low-noise block downconverter only, and it requires a separate feedhorn to collect the signal from the dish. An LNBF integrates the feedhorn and the LNB into a single unit, so no external feedhorn is needed. In modern consumer and DTH installations, most "LNBs" sold today are technically LNBFs with the feed built in.
The distinction matters mainly for larger or professional dishes. Prime focus and large C-band systems often use a separate feedhorn (with an orthomode transducer or scalar ring) bolted to a standalone LNB, allowing installers to fine-tune the feed and mix components. This modular approach suits big dishes where precise feed geometry is important.
For Ku-band offset dishes and standard DTH reception, the all-in-one LNBF dominates because it is simpler to install, weatherproofed as one piece, and pre-matched between feed and electronics. In everyday usage the terms are often used interchangeably, but strictly speaking the "F" indicates the integrated feedhorn.