As the Internet of Things is gaining momentum, low-power communication technologies proliferate. In this paper, we focus on Bluetooth Low Energy (BLE) and IEEE 802.15.4 (CSMA, Low-power listening, and TSCH), and advocate low-power IPv6 for interoperability between the two. We perform a thorough experimental comparison of their link-layer performance, both in idle radio environment and when facing heavy (controlled) external interference. Our results suggest that both technologies can achieve interesting and complementary latency-energy trade-offs. Based on our results, we discuss possible interoperability between BLE and IEEE 802.15.4 and present related open issues.