For instance, consider the 400mm versions of each:
According to their descriptions, they each have the same inner and outer dimensions as the other. At the moment they are both $9.99, but normally the grey one is $4 more. Is there any difference between the two of them other than color and sometimes price (when the grey one isn’t on sale)?
Without any objective information from BL, we are left with subjective information.
I imagine it is slightly easier to see the filament in the white PTFE tube.
However, there is one important difference they do not state.
The A series printers come with grey PTFE tubes and the P series and AMS units come with white PTFE tubes. I assume the X series comes with white as well.
Colour matching seems to be the difference. The cost difference (outside of the sale) doesn’t seem reasonable.
gurrrl, color coordination is important
Yep 
Rather usefull to be able to see where the filament is in the PTFE under the tinted lid.
There’s a third color: missing PTFE tube. Good luck getting one in this case. One month since I bought an A1 with missing items and still no solution from the (poor) Bambulab customer service.
