Someone told me that when grandmasters play each other they don't play off the book they make moves differently. Let's say GM 1 plays the ruy lopez but plays it differently by making a different move and GM 2 master plays the stienitz defense (just an example), how can a person do that by making a different move without making a blunder? Can this be true or no?

What you heard is likely a reference to novelties that GMs research and keep under their hats until a major tournament. These are new lines, or lines the current book knowledge might indicate are inferior (but for which the GM may have a new variation calling that into question).

It's not so much an issue of playing incongruent openings, but rather experimenting with me ideas within existing openings.

Can you also do this in game databases aswell also

TheGrobe wrote:

What you heard is likely a reference to novelties that GMs research and keep under their hats until a major tournament. These are new lines, or lines the current book knowledge might indicate are inferior (but for which the GM may have a new variation calling that into question).

It's not so much an issue of playing incongruent openings, but rather experimenting with me ideas within existing openings.

When a grandmaster makes a new move in the opening that is not in the book, its called a novelty. Its probably to take the opponent out of book and trying out new ideas. As long as the new move doesnt give the opponent any sort of advantage its not considered a blunder. 

Ok give me an example what new move should it consist of in book play

finalunpurez wrote:

When a grandmaster makes a new move in the opening that is not in the book, its called a novelty. Its probably to take the opponent out of book and trying out new ideas. As long as the new move doesnt give the opponent any sort of advantage its not considered a blunder. 

basically a new move that doesnt lose :P

I have made a few novelties but most of them give away the advantage as white or lose as black. Still it can be nice to have a good surprise move