Illustrated list of differences between the arcade and NES versions of Super Mario Bros

A comprehensive collection of maps for every level of Vs. Super Mario Brothers can be found on the TheMushroomKingdom's Vs. SMB Map Page. The maps detail every last inch of every single level including enemy positions and also list the location and contents of every item block both visible and hidden. Other tidbits of info are given on the individual map pages such as whether the level was only altered slightly from the regular SMB game or replaced entirely.

The levels that were replaced from the regular version of the game were actually pulled from the Japanese SMB2 which wasn't sold in the west because it was considered too difficult for non-Japanese kids. (Although it was eventually released in the west as as "The Lost Levels"). Funny enough, they were still altered slightly to make them a bit easier because the Japanese levels were considered too hard even for a a game designed to munch quarters. The maps of the replaced levels found at the link given state which level from the Japanese game it corresponds to, and the site also offers an equally comprehensive collection of maps for both Super Mario Bros. and the Japanese Super Mario Bros 2 making it easy to compare the details and differences side-by-side.

Some of the other differences between Vs. SMB and 'regular' SMB according to that site are are: More enemies added in most levels, bug fixes/prevention, no warp to World 7 or 8, new required paths in "maze levels", and less power-up and 1-Up chances.