oesophageal veins vs esophageal veins

oesophageal veins and esophageal veins both are nouns.

Word	Noun	Adjective	Verb	Adverb
oesophageal veins	Yes	No	No	No
esophageal veins	Yes	No	No	No

As nouns, oesophageal veins and esophageal veins are synonyms defined as:

oesophageal veins and esophageal veins: small veins from the esophagus emptying into the brachiocephalic vein or the azygos veins

Other synonyms of oesophageal veins include venae esophageae.

oesophageal veins (noun)	esophageal veins (noun)
small veins from the esophagus emptying into the brachiocephalic vein or the azygos veins	small veins from the esophagus emptying into the brachiocephalic vein or the azygos veins