ICF coaches are the older design built at the Integral Coach Factory in Chennai from the 1950s; LHB coaches are the stainless-steel design licensed from the German firm Linke Hofmann Busch and built since 2000, rated for 160 km/h, with anti-climbing couplers and a quieter ride. Indian Railways is replacing ICF stock with LHB across the network.
For a passenger the visible difference is the berth count: 72 versus 80 in Sleeper, 64 versus 72 in 3A, 46 versus 54 in 2A. That changes which berth numbers are lower, middle, upper or side, which is why a berth position finder has to know the coach type.
Also written or searched as: LHB coach · ICF coach · LHB meaning · LHB vs ICF