The main difference between LTE-M and NB-IoT is the frequency bandwidth. As the name NarrowBand suggests, the frequency bandwidth for NB-IoT is considerably lower than for LTE-M. The data throughput rate is also higher with LTE-M, with up to 1 Mbit/s. For NB-IoT, the data rate is much lower, at up to 128 Kbit/s.
In terms of building penetration, NB-IoT performs better than LTE-M and is therefore predestined for stationary applications, especially in buildings and basements. LTE-M scores particularly well in mobile IoT applications because the technology supports what is known as “handover,” i.e., seamless radio cell switching without interruption.