A flight controller is designed to connect to the computer using one of the following 2 methods: CP2102 (CP2103) or VCP. This is how you can tell them apart.
All FC’s use one of the two types of USB connection, CP210X or VCP. Each type requires different driver to install on your computer. Also it’s useful to know in case your USB port is broken and you need to connect to the computer.
Further Reading: How to choose an flight controller for mini quad
How to Tell if You have CP210X or VCP ?
CP210X is a chip as the interface between the FC and computer for configuration and firmware flashing. It’s common in older boards like the Seriously Pro Racer F3 (SPRF3) and Naze32 have a on board which is used.
Driver – Silabs CP210X – http://www.silabs.com/products/development-tools/software/usb-to-uart-bridge-vcp-drivers
For CP210X, you will notice UART1 has MSP enabled for communicating with the computer when USB port is connected. That’s also why you don’t want to connect any other devices to this UART if you have this type of FC.
Modern flight controllers use VCP (Virtual COM Port) to configure settings, and use DFU mode to flash firmware. These interfaces are integrated features in the MCU.
For VCP boards, you will see USB VCP in the port tab which has MSP enabled. VCP has the advantage that the USB connection is not shared with UART1 so you don’t need to worry about using it for something else.