Capillary tube and Capillary vessel

Capillary tube noun - A tube of small internal diameter; holds liquid by capillary action.

Capillary vessel and capillary tube are semantically related. In some cases you can use "Capillary vessel" instead a noun phrase "Capillary tube".

Capillary vessel noun - Any of the minute blood vessels connecting arterioles with venules.

Capillary tube and capillary vessel are semantically related. You can use "Capillary tube" instead a noun phrase "Capillary vessel".