According to the sources I ve found listed above your assertion is the wrong way round A pentagram is a five pointed star but a five pointed star may or may not be a pentagram for it to be a pentagram from Greek pentagrammon of five lines it needs to be constructed of five lines only each line crossing two others so that a star of five points is formed with a pentagon in the centre A star is simply A graphic design having five or more radiating points although I would argue that you can have a four or even three point star as well A five point star may or may not have internal lines or polka dots or whatever you want within it