When using the ruler in inches in Photoshop Web, there are five section to an inch (Attachment 1), as opposed to the inch ruler in the Photoshop desktop, which accurately depicts an inch with four sections (Attachment 2). Also, notice the size of the ruler marks in both version.
As a high school photography teacher, im certian this inconistancy will confuse students and make simple measurement or readings uneccesarily difficult and push students away form using the web version of Photoshop.
I'm recommending the inch ruler in Photoshop Web be corrected to resemble the inch ruler in the Phjotoshop desktop app. This is neccessary fix that can easy be corrected and released in a future update.