LCA
British LCAs (Landing Craft, Assault) were similar to the American LCVP, but carried more armor and tended to run lower in the water, thus increasing the chance that the craft would take on water during its time in the choppy English Channel.
Like most landing craft of its size, the LCA was carried aboard larger ships and lowered into the sea by davits. 486 LCAs were used during Operation Overlord, as well as 45 LCA (HR)s and 76 LCSs (LCA variants).
Fact vs. Fiction
Although the film depicts Miller's Ranger's being transported to the beach in LCVPs and LCMs, the real 2nd Ranger Battalion units made their way onto Omaha Beach aboard 2 British LCAs, none of which are seen in the film. The landing craft used by Charlie Company were LCA 418 and LCA 1038. One can assume that no LCAs were available or seaworthy within the short period of time that the production crew had in which to prepare for the film.