Homie device - same as MqGateway - it is not the same as "device" (see below)
Device - sensor or controller connected to MqGateway (e.g. relay module or switch button)
RS485/UART Controller - Additional controller (e.g. Arduino Pro Mini) used to provide communication with MqGateway, for devices which are using other communication channels than simple digital wire (e.g. serial, I2C or 1-Wire).
Point - each place connected to MqGateway with single ethernet/UTP cable, can have many devices connected to it
Room - space containing multiple points, it helps divide configuration into logical parts, but has currently no other influence on how MqGateway works (e.g. kitchen which has multiple light switches)
Wire - single wire of UTP cable which may be used to connect one digital or RS485/UART Controller (requires two wires).