Week 10 's throughline was one question: "When original disappears, where do we restart?" And answer split two axes—how much we can lose (RPO) and how fast we recover (RTO). Backup is RPO reduction game; availability/DR is RTO reduction game. All tools this week were choices on these two axes, at what cost reaching what point.
This review doesn't list concepts; rather reweaves why tools diverge. Then new scenarios in exams become solvable by asking "RPO or RTO problem? Same region or cross-region? Data or workload?"—tool reverse-engineered.