Technically, Lora is a radio modulation scheme - a method of manipulating radio waves to encode information by using a multi-symbol format of chirp.
Sometimes it refers to the LoRa communication network for IoT applications.
In essence, LoRa is a clever way to get very good receiver sensitivity and low bit error rate (BER) from inexpensive chips. This means that using LoRa instead of using other radio technologies of the same price, low data rate applications can achieve a longer range.
Sometimes people also say LoRa, what they mean is LoRaWAN.
But LoRaWAN is different. It is a media access control (MAC) layer protocol built on the basis of LoRa, and built by using Semtech's LoRa modulation scheme. However, LoRaWAN is rarely used in industrial (private network) applications. It is more suitable for the public WAN because all channels are tuned to the same frequency; for single-zone use, it is best to have only one network running to avoid collision problems.
Is LoRaWAN the best wireless technology for your IoT device?
Technically, LoRa is a unique (and awesome) modulation format.
Because all gateways in the network are bound to the same server, deciding which gateway should respond to the transport is the job of the server. In a large network, any given transmission is usually heard by multiple receivers; then the server tells one gateway to respond and the other gateways ignore the transmission. This process is helpful to avoid downlink and uplink collisions because a single gateway is transmitting and overlapping gateways can simply monitor other transmissions.
Many people don't realize that there is a way to use the underlying technology of LoRaWAN - LoRa instead of LoRaWAN. For example, Link Labs' Symphony Link uses a proprietary MAC layer on top of Semtech's chips and has other functions that make it more suitable for enterprises and industrial customers who need to securely connect their IoT devices to the cloud. There are many companies that use LoRa chips for other protocols; all you have to do is find them.