Tosfas at the end of the first perek in Kidushin on the bottom of amud beis says that by the jews good machshovos are taken as actions but not bad which is the reverse by goyim. Explains the Maharsha that the Jews are basicly good, so if they think good, they will do it, but not bad. The opposite is true by the goyim. The Jews have 613 mitzvos because they are able to do it. They have a higher level of nashomo.
