As with so many things "it depends", but from what I've seen visiting coastal fortifications around the world the general trend was to design against an infantry assault (so lighter structures, firing ports, interlocking fields of fire, ditches etc.) or nothing if a landward attack wasn't expected (particularly smaller batteries). That said, looking at coastal forts in Spain I got the impression that they simply designed and built to a common standard all round, it was in the placement of artillery that differences were seen.