What is the difference between mac and radio commands in RN2483?

I am trying to send a message to my application using OTAA encryption mechanism through RN2483 LoRaWAN microchip and STM32 microcontroller. However, command line reference mentioned that how to transmit command which include both mac and radio command

mac tx <hex_data>

radio tx <hex_data>

Question:

  1. Does mac and radio commands are used for the same purpose?
  2. Do I need to have a gateway here?
  3. What is radio command use here? and how it will work?

No, mac sends LoRaWAN packets. Radio sends Lora data.

To use TTN you need to be within range of a gateway connected to TTN.

to the server from gateway?

No. Radio sends plain Lora. Plain Lora does not know a concept like server and gateway. Plain Lora is just a radio modulation that allows sending bytes from one Lora device to another Lora device.
LoRaWAN adds concepts like a standard packet format, standard settings for spreading factor, bandwidth etc and concepts like nodes, gateways and back-end infra structure.

ok for this method, i need to register 2 lora devices to gateway?

No. If you use radio commands you do not require a gateway.

Have you read a basic introduction to Lora and LoRaWAN? If not, please search for it and read up on the difference and on what is involved in LoRaWAN so you are familiar with the concepts.

ok thank u @kersing