From Structure to Meaning
August 24, 2025

Why a Semantic Digital Twin Is More Than a Digital Twin

Understanding the Difference and Why It Matters

When people think of a digital twin, they often imagine a picture of reality — a 2D diagram of a process or a 3D rendering of a machine. These are useful representations. They show what exists and sometimes what’s happening.

But a picture — no matter how detailed — is not enough to make decisions. To move from observing to acting, we need more than a mirror of reality. We need to understand how things are connected, what depends on what, and what those connections mean.

Seeing vs. Knowing

Think about a grocery store. A photo of the shelves shows you what’s in stock. But to manage the store, you need more than the picture — you need to know which items are fresh, which are about to expire, where they came from, and which batch was recalled. Only then can you take the right action.

That’s the difference between a digital twin and a semantic digital twin. One shows you the shelves. The other helps you run the store.

Why Semantics Change the Game

Semantics means adding meaning to data. It’s about connecting things in a way that reflects how the real world works: not just “this exists,” but “this depends on that” or “this failure impacts these customers.”

Without meaning, machines are left to guess. And when they guess, they get it wrong. This is the accuracy gap — the reason digital twins built only on pictures, documents, or raw data lakes fall short. They might look impressive, but when you ask them to reason, they hallucinate connections that aren’t really there.

In automation, that’s not a cosmetic issue. It’s a foundational flaw.

From Data to Decisions

Consider a hospital. Monitoring vital signs gives a snapshot of a patient. But without connecting those vitals to medical history, diagnostics, and treatments, doctors can’t determine the root cause or decide the next best action. A true model of care needs the relationships, not just the readings.

Or take a power grid. Detecting that a line is down is one thing. But unless you connect that line to substations, household circuits, and demand patterns, you don’t know which neighborhoods are impacted or how to prioritize restoration. Only by linking dependencies can operators act with confidence.

In both cases, semantics transform monitoring into understanding — and understanding into action.

The Foundation for Trustworthy Automation

As industries pursue automation and autonomous systems, the difference becomes critical. A twin that only shows the picture cannot be trusted to make decisions. A semantic digital twin, built on meaning, relationships, and accuracy, provides the foundation for:

  • Reliable reasoning
  • Trustworthy automation
  • Decisions you can stand behind

Without semantics, a twin is just a reflection of reality. With semantics, it becomes an engine of intelligence.

And when machines are empowered to act on our behalf — whether rerouting traffic, allocating energy, or restoring a service — accuracy is no longer optional. It’s the difference between fixing a problem and creating a new one.

Telecom: Where Semantics Make or Break Automation

Nowhere is this distinction more urgent than in telecom. Networks are vast, multi-domain, and constantly changing. Operators today are setting bold ambitions around autonomous networks, Dark NOCs, and AI-driven operations. But these visions collapse if they’re built on data that’s only documented, not understood.

A digital twin that’s just a diagram of network elements or a giant data lake won’t reliably answer the hard questions: Which customers are impacted by this fault? What’s the root cause? What’s the best reroute to protect critical services?

Without semantics, reasoning on raw data is fragile — and fragile foundations can’t support automation at scale.

With semantics, operators gain the trustworthy foundation needed for autonomy: one where AI agents can reason, automation can act, and leaders can trust the outcomes. Telecom, with its complexity and criticality, is the perfect stress test for these ideas — and it shows why semantics is not a luxury, but a necessity.

And this is where many of the industry’s biggest myths about digital twins begin - myths we’ll unpack in a future article.

Xanthos N. Angelides

Xanthos N. Angelides

EXFO, Business Development Manager

Xanthos is a Business Development Manager and seasoned technology leader with over 25 years of experience in telecoms. Starting his career as a consultant, he went on to lead roles in product, pre-sales and delivery. He has supported telecom operators worldwide in their journey toward automated operations and digital transformation. As an advocate of semantic digital twins, Xanthos draws on his experiences working with operators to improve operational efficiency and underscores their vital role in enabling the industry’s autonomous networks ambitions.