A fake invoice lands in an inbox on a Tuesday afternoon. Someone opens the attachment, a script runs for nine seconds, and then nothing visible happens. Whether your security stack catches that moment depends far less on brand names than on how the tool thinks about threats. Traditional antivirus asks, "Have I seen this file before?" Endpoint detection and response asks, "Does this behaviour make sense?" That single difference shapes everything else: what you pay, who has to watch it, and whether it fits a ten-person office or a hospital network.
Here is a side-by-side look at both approaches, written for the person actually choosing and running the tools.
How Each Tool Sees a Threat
Antivirus software works primarily by comparison. It holds a library of known malicious files, hashes and patterns, and checks the files your computer touches against that library. Modern versions add heuristics and cloud lookups, which helps, but the foundation is recognition: something has to be known — or at least resemble something known — before it gets blocked.
EDR agents sit lower in the operating system and watch continuously. They record process creation, parent-child relationships between programs, command-line arguments, registry changes, network connections and file writes. Nothing needs to be recognised as malware for the agent to capture it. Detection comes later, from rules, behavioural models or a human analyst reading the timeline.
What antivirus does well
- Fast, low-overhead scanning of files and downloads
- Blocks the bulk of commodity malware before it runs
- Requires almost no configuration to be useful
- Usually included with the operating system or bundled by an IT provider
What EDR adds
- Visibility into fileless attacks that never write a malicious file to disk
- Detection of script abuse, such as PowerShell launched by a document
- Response actions: isolating a machine, killing a process, quarantining an artefact
- A searchable record of what happened, useful for cleanup and for proving scope
Detection in Practice: Two Scenarios
Consider a document with a malicious macro. Antivirus may scan the file, find nothing in its library, and allow it. When the macro spawns PowerShell to download a payload, an EDR agent sees Word as the parent process of a shell command reaching out to the internet — an odd combination worth alerting on.
Now consider ransomware. Antivirus might block a known ransomware binary. EDR may not stop the first encrypted file, but it can flag a single process rapidly modifying hundreds of documents and isolate the host within seconds, which is often the difference between a bad afternoon and a bad quarter.
The trade-off is noise. Behaviour-based detection produces false positives, because legitimate administration sometimes looks like an attack. A quiet antivirus console and a busy EDR console are both normal; only one of them requires somebody to read it.
Cost: Licences Are Only Part of the Bill
Antivirus is cheap per endpoint, and often free when it comes bundled with Windows or a managed IT contract. EDR licences cost meaningfully more per device, and managed detection and response — where a provider watches the alerts for you — costs more again, usually as a monthly per-endpoint fee.
The bigger number rarely appears on the invoice. EDR consumes staff time: triaging alerts, tuning rules that fire too often, investigating the ones that matter. If nobody owns that work, you have bought telemetry, not protection. When comparing quotes, estimate the hours per week each option will consume and put a value on them. That comparison usually decides the question.
Staffing: Who Watches the Console at 2 a.m.?
Antivirus asks almost nothing of you. Updates run, definitions refresh, and the occasional pop-up gets dismissed. A small business can genuinely deploy it and stop thinking about it.
EDR is a different job. Someone must review detections daily, decide what is benign, and know how to isolate a host without shutting down the finance team during month-end. That person does not need to be a threat hunter, but they need curiosity and a documented process.
Three realistic models exist:
- In-house owner. One person, often in IT or operations, with EDR as a named responsibility rather than a side task.
- Managed service. An outside provider monitors and triages, escalating real incidents to you. Costly, but it closes the after-hours gap.
- Lighter tools. Managed endpoint protection with basic response features, sitting between classic antivirus and full EDR.
Be honest about which one you can sustain. A sophisticated tool nobody reads is worse than a simple tool that blocks the obvious things, because it creates false confidence.
Which Fits Your Business?
Antivirus remains a reasonable baseline for a small office with standard risks: email, browsers, a file share, nothing sensitive beyond the usual. Add strong patching, multi-factor authentication and tested backups, and you have covered most everyday threats.
EDR earns its cost when the stakes rise. That includes handling client funds or health information, running servers that face the internet, employing remote staff on personal devices, or operating in a sector attackers target deliberately. It also helps when you have already had an incident and need to answer the question, "What exactly did they touch?"
A shortlist of questions before you commit:
- Who reads the alerts on a Saturday?
- Does the tool cover the operating systems and cloud workloads you actually run?
- Can you isolate a machine in one click, and have you tested it?
- What does onboarding involve, and how long until the tool is tuned?
- Does it integrate with your existing ticketing and backup tools?
- What is the exit path if you change vendors next year?
Building a First Stack Without Overbuying
Start with the fundamentals, because no endpoint tool compensates for missing backups. Verify that your backups actually restore, turn on multi-factor authentication everywhere it is offered, and patch promptly.
Then layer protection in stages. Deploy antivirus or the built-in operating system protection first, confirm it is running on every device, and close the gaps you find. If your risk profile calls for more, move to a managed endpoint product with response features and a provider who will watch it, rather than buying a full EDR platform and hoping someone finds the time to operate it.
Whichever you choose, test it. Simulate a suspicious download, check that the alert arrives, and time how long it takes to isolate the device. Tools are judged on the day they are needed, not on the day they are purchased.
Photo: cottonbro studio / Pexels
