§1 The Terminology Problem - Why These Two Words Blur Together
Before comparing them, we have to admit the obvious: the industry uses these terms loosely. Search any supplier catalog and you will find a single product titled something like "FTTH Fiber Distribution Box / FAT / OTB / FTB." On our own site, several distribution boxes are filed inside the termination box category. This is not sloppiness - it reflects a genuine reality: the two enclosures share most of their internal hardware. Both fix the incoming cable, both hold a splice tray, both present adapters, and both manage bend radius.
So the labels overlap because the hardware overlaps. What does not overlap is the function in the network. Here is the terminology map to align on before reading the rest:
| Term | Stands For | What It Actually Means |
|---|---|---|
| FTB | Fiber Termination Box | A box that terminates fibers and presents connector ports. No splitting. |
| OTB | Optical Termination Box | Synonym for FTB. Common in Southeast Asian and Middle Eastern procurement. |
| FDB | Fiber Distribution Box | A box that distributes one feeder into many drops, usually via a PLC splitter. |
| FAT | Fiber Access Terminal | An outdoor (pole/wall) distribution box. Functionally an FDB built for the field. |
| ODF | Optical Distribution Frame | A different animal - a rack-mounted, high-density frame in the central office, not a field box. |
§2 The 3-Axis Comparison: Function, Position, Splitter
Forget the names. These three axes are the entire difference. If you internalize this table, you will never mis-order again.
| Axis | Fiber Termination Box (FTB) | Fiber Distribution Box (FDB / FAT) |
|---|---|---|
| Core function | Terminate & connect - splice incoming fibers to pigtails, present them on adapter ports | Split & distribute - divide one feeder fiber into multiple drop outputs |
| Signal topology | One in → one out (pass-through / cross-connect) | One in → many out (branching) |
| Contains a PLC splitter? | No - splice trays & adapters only* | Yes - a 1×8 / 1×16 / 1×32 PLC splitter is the defining component |
| Network position | Last leg: building entry, MDU riser, subscriber premises, data-center wall | Distribution layer: street cabinet, pole-top node, between feeder and drops |
| Typical core count | 2–24 cores (often 2–4 at the subscriber end) | 8–24 drop ports + 1–2 feeder inputs + splitter slot |
| Users served | One subscriber, or a small fixed group | Multiple subscribers from a single feeder |
| Mounting | Wall, flush, or rack (indoor-leaning) | Wall or pole, hardened for outdoor (IP65–IP68) |
| Insertion loss added | ~0 dB (connectors/splices only) | Splitter loss - e.g. ~11 dB for 1×8, ~14 dB for 1×16 |
*The asterisk matters: many compact FTTH boxes can accept a small splitter. That hybrid case is §5. The clean definition above is the starting point, not the whole story.
§3 Two Scenarios That Make the Difference Concrete
Scenario A - MDU building entry (termination box)
A drop cable from the street reaches a 12-unit apartment building. The fibers are already split upstream at a street cabinet. At the building you need to splice the incoming cable to pigtails and present clean SC/APC ports so each unit's drop can be patched. No branching happens here - the split already occurred. This is a termination box. Core count tracks the units served plus growth headroom; a 12–24 port wall-mount FTB is typical.
What goes on the PO
A wall-mount FTB, 12–24 ports, SC/APC adapters, IP65 if the entry point sees weather, IP40 if it is a clean indoor riser. Fire rating (UL94 V-0 housing) matters more than IP rating in an indoor riser. No splitter line item.Scenario B - Street/pole distribution node (distribution box)
One feeder fiber arrives at a pole serving a cluster of 16 homes. Here is where the one-to-many split must happen. The box needs to hold a 1×16 PLC splitter, accept the feeder input, and present 16 drop-cable ports - all hardened against UV, rain, and temperature swing. This is a distribution box (or, since it is pole-mounted outdoors, a FAT). The splitter is the reason the box exists.
What goes on the PO
An outdoor FDB / FAT, 16 drop ports + feeder input, pre-loaded 1×16 PLC splitter (SC/APC, G657A2 pigtails), IP65 minimum - IP68 for pole-top or below-grade. UV-stabilized PC+ABS or PP+GF housing. This is one line item that includes the splitter, not two.§4 Where the Overlap Is Real - Hybrid Boxes
The clean definition in §2 has one honest exception. Many compact FTTH boxes are built to do either job: they include a small tray slot that accepts a 1×2, 1×4, or 1×8 mini PLC splitter if you want one, and function as a plain termination box if you do not. This is why a single product legitimately carries both labels.
This flexibility is useful - one SKU covers both roles, simplifying inventory - but it creates the procurement trap: buyers assume "it has a splitter slot" means "it ships with a splitter." It usually does not. Splitters are specified separately unless you request a pre-loaded configuration.
§5 Matching Real Products to Each Role
If you need a termination box (pass-through, no split)
If you need a distribution box (one-to-many, splitter inside)
For outdoor splice protection upstream of either box
§6 Related Reading
IP ratings, materials, indoor vs outdoor, and the procurement checklist that covers every box type.
Why a distribution box adds loss - the splitter math behind the insertion-loss numbers in §2.
Centralized vs cascaded splitting - where the FDB and FTB sit in the architecture.
How to place the access terminal (FAT) relative to the subscriber's ONT.
§7 FAQ
Termination Boxes & Distribution Boxes - Factory Direct
Glory Optical - vertically integrated manufacturer in Ningbo since 2008. FTB termination boxes, FDB/FAT distribution boxes (loaded or unloaded), matching PLC splitters 1×2 to 1×64, and IP68 splice closures. Shipped to operators and ISPs in 50+ countries. Tell us where the box sits in your network and we will confirm the right type before you order.
