I would like to know more about the differences between "NEW dell xps 15" and "dell for 15" (work/entreprise version)
Are they the same device? So why one is called new and the other doesn't?
They are fundamentally similar, but systems sold for work/business often include business-centric support options (including extended support, faster support), along with options generally not included on consumer models (such as a trusted platform module). The features vary by model (with the XPS 13, the only way to get the fingerprint reader is in the business model).
If you're looking for something specific, be sure you verify its presence in what you buy, as some options CANNOT later be added.
At least in the US, you'll get a TPM whether you order it from the Home or Work stores. But ejn63's answer above is correct. Other options that can vary are things like business systems only come with Win10 Pro and often allow you to decline all types of trial software (anti-virus, MS Office), whereas home systems often bundle at least trial versions of those because I imagine the vendors of those products pay Dell to do that, since having the trial installed undoubtedly brings those vendors some additional customers. Otherwise, in some cases the word "NEW" is shown to specifically identify the new model while the old one might still be on sale. So for example when the XPS 15 9570 first launched, it would have been tagged as "NEW", while the previous XPS 15 9560 would have been listed as just "XPS 15" alongside it for a while -- but I don't think Dell is selling the 9560 as a brand new system anymore, only via the Dell Outlet.