The main similarity between these two plans is that both are in favor of democratic governments with free elections. The major difference is that the Plan of Guadalupe is less detailed politically and has a slightly different aim.
The Plan of San Luis Potosi needed to be more detailed because it had to announce what a new government of Mexico would look like after Porfirio Diaz was ousted from power. Therefore, it was longer and more detailed. Its major point was the promise of "effective suffrage and no reelection."
The Plan of Guadalupe also supports a democratic government, but does not do so in any very detailed way. Its goal is to restore the government to what it had been under Francisco Madero, before he was overthrown by Victoriano Huerta. Therefore, its main thrust is a promise to restore what already had existed, not to create something new.
thanks..your answer really helped!