<blockquote><blockquote> it doesn't say anything about 6.1/7 differences</blockquote>
This link shows the difference between the two, hence "What’s new in Safari and WebKit" phrase.</blockquote>
Where does it show any difference? I don't see it.

<blockquote><blockquote> i.e. 537.71, what is your source?</blockquote>
For Safari 6.0 and Safari 7.0 but Safari 7.0.1 is 537.73 and we do not specify the third dot</blockquote>
Safari 6.1 not 6.0. Also, 6.1.1 has 537.73, just like 7.0.1. They're kept in parallel.