How does Bluetooth Low Energy (BLE) differ from Classic Bluetooth?

BLE (Bluetooth Low Energy) was designed for IoT and wearables with ultra-low power consumption. Key differences: Power consumption is much lower in BLE (can run for years on coin cell). Connection time is faster (~3ms vs ~100ms). Data rate is lower (1-2 Mbps vs 3 Mbps). Topology supports broadcast and mesh (BLE Mesh) vs point-to-point. BLE uses 40 channels (2 MHz spacing) vs 79 channels (1 MHz) for Classic. Sleep current is ~1µA in BLE. BLE is optimized for small, infrequent data transfers (sensors, beacons), while Classic Bluetooth suits continuous streaming (audio). Both can coexist in dual-mode devices.