Trouble deciding between XC and road helmet
My current helmet is the Stratus, and I use it for both road and xc mountain riding.  To answer your question about those two helmets specifically, I do believe they are the same shell with the only difference being the presence or absence of the visor.

More generally, (traditional) road helmets typically provide slightly better ventilation while dedicated mtb helmets offer slightly more coverage for the back of your head.  As Carel's comment points out, mtb visors can also obstruct your vision when riding in a more aggressive road position.  Note that all of these difference are minor and that comfort and fit trump getting the correct "type" of helmet*.

*to an extent - more extreme forms disciplines of MTB require a full face helmet and should not be done with a basic road helmet