The BETWEEN range ends at 'V'. If you have a vendor with exactly this value then it will be included. Vendors called 'V' + anything else will be excluded because they sort after 'V', outside your range. As an experiment, try BETWEEN 'N' AND 'W', which will return all the vendors beginning with 'V' and any vendors which are just 'W'.
There's another way to collect all the vendors beginning with 'V', and that's to follow it with a character which would sort after the letters, something like BETWEEN 'N' AND 'V'+CHAR(255).
For fast, accurate and documented assistance in answering your questions, please read this article.
Understanding and using APPLY, (I) and (II) Paul White
Hidden RBAR: Triangular Joins / The "Numbers" or "Tally" Table: What it is and how it replaces a loop Jeff Moden