EDR vs MDR: The Simple Difference, and Which One You Need

EDR and MDR sound almost identical, and the two terms often get used interchangeably. The short explanation: EDR is the tool, and MDR is the service that operates it.

EDR is the tool

Endpoint detection and response is software that runs on laptops and servers. It watches what happens on the machine, keeps a detailed log, and raises a flag when something looks suspicious. Microsoft Defender for Endpoint, Palo Alto Cortex XDR, and SentinelOne are common enterprise examples, and there are several other strong platforms in the category. It is a capable piece of technology, and having it deployed is a real step forward for any team.

It helps to see where EDR sits next to the tool most people already know. Antivirus is designed to block, and it blocks conservatively so it does not disrupt legitimate work. EDR takes a different job: rather than making the block-or-allow call itself on ambiguous activity, it records that activity in detail so it can be reviewed. That design is deliberate and useful, and it points to the one thing EDR is built to work with: someone to do the reviewing.

MDR is the service that operates the EDR

Managed detection and response supplies the reviewing and the response, and more. It is a service in which an external team aggregates the logs, writes and tunes the detection rules that decide which activity deserves an alert, monitors around the clock, and responds when something fires. Providers like Arctic Wolf and Field Effect are examples of this model. Because an MDR provider watches across many companies at once, they gain an advantage a single deployment cannot: when a new threat appears at one client, they can search everyone else's logs for the same signs.

MDR carries through to the response itself, including acting remotely on the affected machine, so containment does not wait on someone being physically at the keyboard. That reach, from detection into hands-on response, is the part a service adds on top of the tool.

EDR vs MDR at a glance

EDR generates the visibility: the logs, the flags, the raw signal from every endpoint. MDR turns that signal into outcomes: rules that decide what matters, eyes on it at all hours, and a response when it counts. A team can run EDR on its own and get real value from the visibility. Pairing it with active response, built in-house or brought in through MDR, is what completes the capability.

The frameworks describe the same two halves. NIST CSF 2.0 separates continuous monitoring (DE.CM), assets being watched so anomalies are found, from incident management (RS.MA), responding once they are. SOC 2 does the same: CC7.2 covers monitoring that detects anomalies, and CC7.3 covers evaluating events and responding to them. Both standards treat detection and response as things that operate continuously, which is exactly the pairing of tool and service in plain language.

To build an MDR service  in-house requires the  following:

1. Generate the right logs at the source. Turn on audit logging where it is off, so the activity worth watching is actually recorded.
2. Ship the logs to a central repository like a SIEM. Get them off the machine that generated them, so they stay available even if that machine is affected. Keep them live and queryable for roughly 90 days, then archive to lower-cost storage for around two years once live retention gets expensive.
3. Build detection use cases on top of the collected logs. A detection use case is a specific rule that says a particular combination of events should raise an alert for a person to look at. Use cases are what turn a stream of raw logs into a manageable set of things worth investigating.
4. Respond when one fires. Someone receives the alert, decides whether it matters, and acts, at any hour.
   
   

Frequently Asked Questions

What is the difference between EDR and MDR?

EDR is a software tool that runs on your endpoints, logs activity, and flags anomalies. MDR is a managed service in which an external team reviews those flags, tunes the detection rules, monitors around the clock, and responds when something fires. EDR gives you visibility; MDR adds the people and the response on top of it.

Do I need MDR if I already have EDR?

Not necessarily, but EDR only delivers full value when someone operates it. If no one reviews the alerts or responds at all hours, the visibility EDR provides is not being turned into outcomes. You can staff that work in-house or bring in MDR. For smaller teams without a dedicated security operations function, MDR is often the faster route to a complete capability.

Is Microsoft Defender an EDR or an MDR?

Microsoft Defender for Endpoint is an EDR: a software tool that detects and logs activity on the machine. It is not a managed service on its own. Pairing it with a team that monitors and responds, whether internal or an MDR provider, is what completes detection and response.

What does an MDR service actually do?

An MDR provider aggregates your logs, writes and tunes detection rules, monitors 24/7, and responds when an alert fires, including acting remotely on an affected machine. Because they watch across many companies at once, they can spot a new threat at one client and check everyone else for the same signs.

How do SIEM, EDR, and MDR relate to each other?

They sit at different points in the same flow. EDR generates logs at the endpoint. A SIEM is the central repository those logs are shipped to and queried in. Detection use cases run against the collected logs, and response acts on what they surface. MDR is one way to buy the operation that runs the detection and response steps for you.

Can a small team run detection and response without MDR?

Yes, but it is a multi-quarter effort. It means generating the right logs, shipping them to a SIEM, building and tuning detection use cases, and staffing response at all hours. Security monitoring and detection engineering are a discipline in their own right, which is why many small teams choose to bring in an MDR provider rather than build the operation from scratch.