Well this is one definition�from the Urban Dictionary:

The Battle of Alberta is the one-sided rivalry between the cities of Edmonton, Alberta and Calgary, Alberta. It is most famous for the battles between the NHLs Edmonton Oilers and Calgary Flames, and to a lesser extent the Edmonton Eskimos and Calgary Stampeders.

Why is it so one-sided? Because Edmonton has consistently kicked Calgarys ass in the NHL and CFL playoffs. The Flames have yet to win a playoffs series cleanly against the Oilers, and the Stampeders are a joke compared to the crown jewel of the CFL; the Edmonton Eskimos.

Here is another definition from Wikipedia:

One of the most intense and passionate expressions of this rivalry is the frequent matchups between the professional NHL hockey clubs based in each city - the Edmonton Oilers and the Calgary Flames.

The Oilers joined the NHL as one of the teams making the switch from the World Hockey Association in 1979, soon followed by the Atlanta Flames moving to Calgary in 1980, suddenly making the question of who would be #1 in Alberta pro hockey a hot topic. The Flames were the dominant squad during their inaugural season, eliminating the Chicago Blackhawks and the Philadelphia Flyers before losing to the Minnesota North Stars in the conference final in the 1981 NHL playoffs. However, the Oilers were already making headlines with their young superstar, Wayne Gretzky, and they swept the heavily-favoured Montreal Canadiens before bowing out in a six game battle to the defending Stanley Cup Champion New York Islanders. The Oilers won the Stanley Cup first. The team that had showed so much promise in the early ’80s finally became champions in 1984, and set the building blocks for the last NHL dynasty with a lineup that included legends like Grant Fuhr, Paul Coffey, and Mark Messier. The Oilers defeated the Flames in the playoffs in 1983, 1984, 1988, and 1991, winning the Stanley Cup in 1984, 1985, 1987, 1988, and 1990. However, the Flames did get revenge; the infamous 1986 Battle of Alberta was decided by an own-goal by Oiler Steve Smith. The Flames went on to lose to the Montreal Canadiens in the Cup final. The Flames eventually won the Cup in 1989 with Lanny McDonald, Doug Gilmour and Mike Vernon leading them. For 8 straight seasons, an Albertan city represented the West in the Stanley Cup final. The last time the two teams met in the playoffs was in 1991, and it is often cited as one of the most exciting playoff series of all time.

With the fortunes of both teams hitting a relative nadir during the 1990s, the rivalry cooled off. The passions ignited in the 1980s playoff sagas would only make brief appearances during the regular season. During the Calgary Flames’ run to the Stanley Cup final in 2004, the Oilers missed the playoffs; but the Oilers made it to their 7th Stanley Cup final in 2006, becoming the winningest team of the Clarence Campbell Trophy. With the new Collective Bargaining Agreement making it possible for both teams to contend, the rivalry has been re-ignited. A new BOA in the 2005-06 playoffs was a possibility but the Calgary Flames lost to the Anaheim Mighty Ducks in the first round.

Overall, the Oilers have five Stanley Cup championships, while the Flames have only one.

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