Complex sentence: Professional clubs compete in the Magners League and the Heineken Cup, while the Scottish Hydro Electric League Championship exists for over 150 amateur and semi-professional clubs, as does a knock-out competition, the Scottish Hydro Electric Cup.
Split into simpler sentences: Professional clubs compete in the Magners League and the Heineken Cup. The Scottish Hydro Electric League Championship exists for over 150 amateur and semi-professional clubs, as does a knock-out competition, the Scottish Hydro Electric Cup.