I recently started looking at NB-IoT as a solution for a project based in the UK. Previous projects have used LoRa for the communications to remote sensors in the field so LoRa is my base for comparison. The research below is not exhaustive and some points may need further clarification. The answers are UK centric and from Jan 2019.

LoRa stands for Long-Range and LoRaWAN adds a standard protocol onto LoRa to ensure interoperability between different manufacturers of products and services. LoRa uses an unlicensed spectrum. This allows tariff-free access to your own network but you may need to pay to use someone else’s network.

NB-IoT is 3GPP’s technology to service the growing interest in IoT and LPWANs. It uses the current 4G networks of the telecom operators but implements some key technologies to improve battery life for IoT applications.

 NB-IoTLoRa
CoverageNB-IoT will only be deployed on 4G basestations. These basestations are mostly covering the urban population at the moment. There is currently poor 4G coverage in many rural areas of the UK.
There is a statement that all Vodafone LTE capable masts will be NB-IoT capable by 2020.
The link budget for NB-IoT is 20dB higher than GPRS so the same basestation will reach further than GPRS.
User needs to install their own network which is easy to do. A complete solution for a Gateway is easy to buy and setup. Gateways cost about $1000 for an outdoor unit and about $300 for an indoor unit. The Gateway only needs power. The Gateway has a range of few km to reach deep indoor nodes and 10-20km to reach outdoor nodes.
MCL (Maximum Coupling Loss)164dBDownlink from Gateway is about 165dB.
Uplink could be 14dB (node Tx power) + 138dB (Rx sensitivity) + 10dB (Gateway antenna gain) = 162dB
Directional SensitivityYes. Mast antenna is directional -> better link in right direction. Poorer link off to the sides.Can be Omnidirectional or Directional depending on antenna. An omnidirectional antenna would get worse coverage compared to the direction of the NB-IoT antenna but better coverage off to the sides.
Access ChargeHave to pay for network access.
Pricing plans have not been released.
Network access is free for own network.
Need to pay for access to networks owned by others.
Data RateDownlink = 234.7kbps
Uplink = 204.8kbps
100kbps max Lower rate gives better range.
LatencyNB-IoT has lower latency than LoRA for uplink only. For downlink NB-IoT will have longer latency.
LoRa is asynchronous. Many nodes can transmit at the same time on different channels or spreading factors and all will be received.
No clear winner on latency.
Power consumptionThe NB-IoT protocol is more complicated than LoRa. This leads to higher power consumption. NB-IoT is lower power consumption than 3G/4G due to features like PSM (Power Saving Mode) and eDRX(Enhanced Discontinuous Reception).
5uA sleep1uA sleep
120-300mA active32mA active.
QoS (Quality of Service)NB-IoT has better QoS. You are paying for frequency spectrum to be dedicated to your application.Frequency spectrum is shared. If someone else is using the same spectrum then you may not always be able to successfully communicate with your node.
Moving assetsNot well suitedHas Geolocation capability
Node CostMore complicated protocol and higher power consumption will increase the cost of nodes compared to LoRa.
Example coverage of an urban Gateway in Copenhagen.
Example coverage of a LoRa GPS tracker as it is driven along a road in Denmark. A sample is highlighted when the GPS tracker is in contact with 6 LoRa Gateways and the furthest is 38.5km distant.

Summary

In the UK, the question of coverage is significant. Neither NB-IoT or LoRa are here yet (as of Jan 2019). It will be deployed by different organisations – Telcom operators for NB-IoT, private companies or local government for LoRa.

Telcom operators will probably not offer full coverage to rural areas for some years if ever.

If you have infrastructure available (buildings with power that can have a small antenna on top of them) to place LoRa Gateways you can control the coverage available to your nodes.

LoRa could be installed today by the end user if they have the infrastructure. NB-IoT is supposed to be available on all LTE capable masts by end 2020. Today (and for some rural areas, for the foreseeable future) the choice is between installing your own LoRa gateways and the 3G/4G network. 3G/4G modules are double the price of NB-IoT modules and consume more power (bigger battery required).

A solution created now that is based on 3G/4G will have significant amount of IP that can be migrated to an NB-IoT solution. 3G/4G solution to NB-IoT solution would halve the module price and reduce battery requirements.

LoRa has lower power consumption which will reduce battery size and price.

https://www.link-labs.com/blog/overview-of-narrowband-iot

https://www.rompagroup.com/news/internet-of-things-part-3-lpwan-technologies.aspx

https://teks.co.in/site/blog/lora-vs-nb-iot-which-iot-standard-has-the-edge/

https://www.bluesignal.com/2017/07/13/nb-iot-vs-lora-its-an-ecosystem-not-a-race/

https://www.sciencedirect.com/science/article/pii/S2405959517300061

http://vbn.aau.dk/files/252193688/vtcSpring17.pdf