one more explanation for a possible difference of the two segments
„visit depth = 2“ is looking for visits with 2 pageviews where the pagenames are not the same! this is because the visit depth does not increase when the pagename of the second pageview is the same, see here: Hit Depth (at the end of the article)
this means that the difference of those two segments you mentioned should be all visits with 2 pageviews having the same pagename.
The segment definitions 'page view' and 'visit' are calculated a little bit differently than most other segment definitions.
These two definitions take a) the date range; and b) overall visitor into consideration. The segment definition 'page view' basically says "take every page view within the date range and organize them by unique visitor". With your segment:
Include all visits where page views = 2
That's basically saying 'whenever a visitor hit their second page view within the date range, include that visit'. Urs's recommendation to use visit depth or hit depth would be my recommendation as well.
Page view = 2 means that the visitor in question fired 2 page views. These could happen on separate visits. So for example, If I visited your site then bounced, then the next day visited your site again and bounced, that would match the segment of 'page view = 2'.