I would suggest that all bible translations are versions, but not all versions are translations. If there is a car accident you may have several versions of the same event, which are all accurate but don't necessarily use the same words. Possibly, the distinction that was being made was that the NWT is by and large a literal translation whereas some other translations are paraphrased.
Interestingly, I think it could be argued that while the English NWT is a translation from the original languages, the NWT in most other languages are versions of the English NWT and not translations from the original languages.
Earnest