Returning Visitors and Export column naming

We are currently confronted with the following uncertainties:

1. Returning visitors
We also have difficulties in measuring the “returning visitors”.
Under Visitors->Engagement, we see the returning visits.
]But: Is there a way to extract the returning visitors?[/i]

Assumption: ‘Returning visitor’ is a subset of, ‘Returning visits’, of ‘Unique visitors’?
Haven’t found anything (doc, faq, forum) which answers exactly this question.

2. Export of pageview statisticts
If we go to Actions->Pages, the first column is named “Pageviews”.

When exporting the data as a CSV-File, the same column is named “nb_hits”.
How come the same figures are named differently?

Quite confusing as to us hits are not the same as pageviews (see also Web analytics - Wikipedia).
Why not naming the columns identically?

(By the way: same for “Unique Pageviews” that are callet “nb_visits” in CSV-File)

Any hints will be appreciated…

Piwik reports returning visits, not returning visitors

unique pageviews = visits which visited the site

pageviews = hits on the page

these are the same things