Two radios under one name
“Bluetooth” covers two separate wireless systems. The Bluetooth Core Specification calls them Basic Rate (BR), with an optional Enhanced Data Rate (EDR) extension, and Low Energy (LE). Most people call the first one Bluetooth Classic.
Both systems include device discovery and connection setup, and both use the 2.4 GHz band. Beyond that they are different radios with different link layers. The specification describes LE as designed for products that need lower current consumption, lower complexity and lower cost than BR/EDR, with lower data rates and lower duty cycles. It also notes that, depending on the use case, one system may suit better than the other.
A Bluetooth controller can be LE only, BR/EDR only, or a combined controller that runs both. A phone that streams to headphones over Classic and reads a fitness tracker over LE has the combined kind.
How the two compare
The Bluetooth SIG publishes a side-by-side comparison of the two radios. The main differences:
| Bluetooth Classic (BR/EDR) | Bluetooth Low Energy (LE) | |
|---|---|---|
| Channels | 79 channels, 1 MHz apart | 40 channels, 2 MHz apart (3 for advertising, 37 for data) |
| Data rates | 1 Mb/s (BR), 2 or 3 Mb/s (EDR) | 1 Mb/s or 2 Mb/s, plus a Coded PHY at 500 kb/s or 125 kb/s |
| Topologies | Point-to-point | Point-to-point, broadcast and mesh |
| Typical uses | Audio streaming, mobile printing | Sensors, wearables, phone-to-accessory data, beacons, location |
The data rates are radio rates, not what an app sees. Protocol overhead, the time each device spends listening, and the radio environment all reduce real throughput. LE’s Coded PHY trades speed for receiver sensitivity: the SIG table lists lower data rates with better sensitivity requirements.
What each one is good at
Bluetooth Classic is the radio behind wireless speakers, headsets and car audio, according to the SIG’s overview. It keeps a steady connection open and moves a continuous stream of data. Android’s Bluetooth guide calls Classic the right choice for more battery-intensive operations such as streaming, and points apps with low power requirements to LE instead.
Bluetooth Low Energy is built around short exchanges and long idle periods. A device announces itself with small advertising packets on three channels, other devices scan for those packets, and a connection carries data only when there is something to send. That pattern is what allows the low power consumption Android’s guide describes for proximity sensors, heart rate monitors and fitness devices.
LE also does things Classic does not. It supports broadcast, where one device sends to any number of listeners without connecting, and it underpins the Bluetooth Mesh standard for building automation. Newer LE features cover direction finding and distance measurement.
Audio is no longer Classic only. The SIG’s LE Audio specifications run audio over the LE radio and add broadcast audio, branded Auracast. Classic Audio still runs on the Classic radio.
Which one apps use to link phones
For an app that moves data between two nearby phones, LE is the usual choice, for practical reasons:
- Both mobile platforms expose it to apps. Android’s BLE APIs cover scanning, advertising and acting as a GATT client or server. On Apple platforms, Core Bluetooth supports LE in both the central and the peripheral role.
- It fits short, bursty messages. Chat messages, sensor readings and sync updates arrive in small pieces, which matches LE’s model of brief exchanges.
- It costs less battery while idle. Devices can stay discoverable without holding a high-duty-cycle link open.
Classic remains an option on Android, where the Bluetooth APIs let apps open RFCOMM channels between devices. On iPhone, Classic accessories that are not covered by Core Bluetooth go through Apple’s External Accessory framework, which is for MFi accessories, and the accessory’s manufacturer decides which apps may talk to it. Those two routes do not meet, so a phone-to-phone design that has to cover both platforms normally runs over LE.
The Offline Protocol mesh SDK, for example, connects iPhone and Android phones over Bluetooth LE and runs its own forwarding protocol on top, rather than Bluetooth SIG Mesh.
Choosing between them
Pick Bluetooth Classic when you need a continuous, high-throughput stream to an accessory that already speaks a Classic profile, such as audio or a serial device on Android. Pick Bluetooth LE when you need low idle power, small messages, discovery without pairing, broadcast to many listeners, or the same design on iPhone and Android. LE’s own building blocks, the central and peripheral roles and GATT, then decide how the devices talk once they have found each other.