Have you checked sys?
1)Go to cd /sys/devices
2) If we find the directory of the ports: find -name "ttyUSB1". It will probably find them in something like ./pci0000:00/0000:00:1d.0/usb2/2-2/2-2.1/2-2.1:1.0/...
The pci* part is the USB controller. The interesting bit is the 2-2.1 which is the USB device.
If you want to differentiate different USB devices, you can differentiate them using their vendor id and product id.
Every usb device has it's unique vendor id and product id.
You can detect it easily using command
Now it will show the id in terms of something like ID 045e:00cb
for every usb device, In this example 045e is vendor ID and 00cb is productid.
a) just run cd /sys/class/tty/
b) readlink ttyUSBn
will give you the full path of the device directory.