Prometheus and OpenTelemetry are two metrics systems used in observability, with Prometheus being a standard tool for monitoring systems and OpenTelemetry offering a more flexible and unified standard for traces, logs, and metrics. While both systems allow code instrumentation via SDKs, OpenTelemetry supports automatic instrumentation without adding code to applications, but also has limitations compared to Prometheus, such as not supporting delta representations or exponential histograms. The two systems can be converted between each other with minimal loss of precision, but some metric types may change slightly. Most organizations will likely mix both standards, and the choice between them depends on priorities such as stability, flexibility, and specific use cases, with Promscale being a long-term store for Prometheus metrics that seamlessly integrates with Prometheus and offers 100% PromQL compliance.