Sorry - the groupset is the type of gears and drivetrain that it has fitted from the most basic shimano 2300 or Sora etc, tiagra, 105, ultegra and dura ace. There are also electronic versions of ultegra and dura ace. Benefits of the better systems are lower weight and smoother shifting. Downsides are cost whereas a cheap set up maybe a couple of hundred pounds and Di2 is a few thousand. There are also similar systems with both sram and campagnolo makes of groupset too.