Answer
The practical way to sort this out is to map specific failure scenarios against business tolerance. A failed disk unit, a bad PTF, or a human error that corrupts a library are HA-shaped problems: the fix is switching processing to a synchronized secondary system, often an LPAR in the same data center or a nearby facility, within minutes. A flooded building, a regional power outage, or a ransomware event that touches production and its immediate backups are DR-shaped problems, because the secondary path has to sit somewhere genuinely independent of the primary site's power, network, and staff.
Cost and complexity scale with both distance and synchronization tightness, so buyers should resist the instinct to buy the most robust option everywhere. A workload that generates modest revenue and tolerates a half-day outage does not need the same design as order entry or manufacturing control. What tends to catch organizations off guard is discovering, after an HA investment, that their DR posture never grew past an assumption that the backups are somewhere else. Journaling and replication technology built for HA can often be extended or repurposed for a DR target, which is a reasonable way to sequence the investment rather than building two unrelated architectures from scratch.