Question

difference Between vasaefferentia and vasadeferentia

Answer 1

What is the difference between vas deferens and vasa efferentia?
These are distinct body parts, but because they have similar functions (to wit, they transport sperm cells from one anatomical structure to another) they have similar names. We most often refer to the former in the singular, as you have done here. There are two of them, however, and if we compare the plural of both names, they are vasa deferentia and vasa efferentia, or ductus deferentes and ductus efferentes.
There's not much difference in what these names mean. They come from the Latin de+ferre and ex+ferre, respectively, both meaning "carry away". The use of the term vas deferens has become so entrenched that the English word "deferent" has come to mean "related to the vas deferens" as in "deferent arteries”. Some similar sounding words such as "defer" and "deference" come from the Latin differre. 
Like it or not, vas deferens has become adopted as the English name. We know this because it is no longer subject to any of the rules of Latin. For example, instead of saying, "both vasa deferentia", we say "both vas deferens". I will go with the flow and act like it's an English term, or even, as is the custom in clinic, use "vas" for short.
No such consensus exists with regard to the vasa efferentia, however. Most articles on the subject begin with a laundry list of possible names. But in this case, we are not compelled to adopt a name from Latin. This is because one of the Latin synonyms for this term, ductus efferentes,has been Anglicized to "efferent ducts", and I see no reason why we should bother with Latin when we have a perfectly good name for something in English.