Lasso Used to make freehand selections. Simply draw a freehand line by holding down the left mouse button and letting go to close the selection. Magic Wand Used to make a selection set based on the color of pixels in the image. Pixels adjacent to the selected pixel and with simlar color will be selected. The selection is made by the amount of tolerance.
Tolerance is how close to the selected pixel's color does the adjacent pixels' color have to be.
Set the tolerance by double clicking on the Magic Wand tool. The setting can be a value from 0 to 255. A setting of 0 will cause the Magic Wand to only select adjacent pixels of the exact same color.