Display of the "Port Parameters" (GetCommState), that's how the last application using this port left it behind and on failure it indicates that the port is in use
Display of the "Default Port Parameters" (GetDefaultCommConfig), these are the parameters from the device manager
Display of the "Port Properties" (GetCommProperties), these are the capabilities of the COM port hardware, e.g. supported signals and data rates
COM1: An on-board port of an Intel Series 8 chipset attached thru LPC which is a sub-set of the historic ISA bus
COM6-7: An OX16AX99100 PCIe card with two serial ports
COM21-24: A 4x USB serial adaptor which is in fact a 4-port USB standard hub with four FTDI one-port serial controllers attached. FTDI controllers are a USB device with a child device exposing the COM port.
COM61-64: A 4x USB serial adaptor which is in fact a 4-port USB standard hub with four Prolific one-port serial controllers attached. Prolific controllers are a USB device which exposes a COM port itself.
COM7-10: A 4x USB multi-serial adaptor which is a USB device exposing four COM port devices.
Using the "Flash Lines" tool you can identify RS232 COM ports by means of a RS232 LED indicator device: