Monitoring is more of a relative, reactive approach which works well against already established thresholds. In contrast, observability tools work by enabling iterative exploratory investigations to systematically determine where and why performance issues may be occurring. Observability enables a proactive approach to identifying any failure mode, whether previously known or unknown. In simple words, Monitoring works well for previously known issues but Observability is for both unknown and known issues.

Monitoring is built on metrics. These metrics are averaged/aggregrated and then rules are defined for them. Based on these rules there are alerts that are triggered. Metrics are also studied in trends, giving us dashboards.