Cycling Weekly does a pretty thorough breakdown in this buyer's guide to groupsets in this video and article.

What is a groupset? Should you pick Shimano, SRAM or Campagnolo? Here's your complete guide to this essential piece of road cycling kit.

What is a groupset?

The term “groupset” or “gruppo” refers to mechanical parts that make up a bike and typically include the gear/brake levers, front and rear brakes, front and rear derailleurs, bottom bracket, crankset, chain and cassette. After the frame, a bike is often defined by its groupset.

Read more at http://www.cyclingweekly.co.uk/videos/cycling-tech/road-bike-groups...