Depending on the year and the repository used, this source reflects either the index (in print or online) or the actual vital records images from Massachusetts from 1841 to 1915 (as of 2009). This date range reflects the earliest date that statewide records were collected up until the most recent year released.
As of 2011, NEHGS (AmericanAncestors.org) has records from the Massachusetts archives split into two databases, for 1841 to 1910, and 1911 to 1915. It appears that the actual images are now connected to the search results for all years. The information available in the records depends on the town and date of the record.
FamilySearch.org has the microfilmed the birth, marriage and death registers from 1841 to 1915 and split them into three different databases respectively.
Both sources purport to have filmed the same records, and the pages filmed appear to be generally identical. There are some differences; for example, the marriage of John F. Kennedy's parents appears on p. 248 in 1914 v.2. That page, as well as, apparently (the film is out of order) pages 210-309 of that volume, are missing from the FamilySearch film and index.