Dictionary.com
Thesaurus.com

cannula vs. catheter

[kan-yuh-luh] / ˈkæn yə lə /
Sometimes canula

noun

Surgery.

PLURAL

cannulas, cannulae
  1. a metal tube for insertion into the body to draw off fluid or to introduce medication.

[kath-i-ter] / ˈkæθ ɪ tər /

noun

Medicine/Medical.
  1. a flexible or rigid hollow tube employed to drain fluids from body cavities or to distend body passages, especially one for passing into the bladder through the urethra to draw off urine or into the heart through a leg vein or arm vein for diagnostic examination.