Real time analytical systems are made to continuously ingest large amount of data (often events) and have low-latency queries. It is sometimes also called product analytics.
It is different from OLAP in how these systems are used, whilst real time analytics really strives for low latency queries, OLAP has no qualms with high latency or batch-loaded (stale) data.
Reference
Kleppmann, Martin, and Chris Riccomini. Designing Data-Intensive Applications: The Big Ideas behind Reliable, Scalable, and Maintainable Systems. Second Edition, O’Reilly Media, 2026.