Every league has two conferences, one named the Great 8 and other the Big 8. There is no relationship between a Great 8 in one league and a Great 8 in another. They could as easily be called Eastern and Western, except that there are no locations associated with BB teams, or they could be called A and B. Maybe in the future, the names could be made more relevant to each country.
As long as you are in your current league, you will remain in your current conference. If you promote or relegate to another league you could end up in the other conference.
During the regular season, a team plays each team in its conference twice (one home and one away) for a total of 14 games; they also play each team in the other conference once (4 at home and 4 away), for a total of 22 league games.
All league games count in the standings, but you will have a ranking 1st to 8th in the Big 8, rather than 1st to 16th in the league. So your two friends in the Great 8 are competing directly against each other, but part of that compeition will include how they do when they play your team.
The top 4 teams in each conference enter the playoffs at the end of the season, with the winner of the playoffs promoting to the next division. The 8th place teams in each conference relegate, and there is a playoff between the 6th and 7th place teams in opposite conferences to determine which relegates.
At mid-season, there is an All-Star game played between players from the two conferences, but that is pretty much a fun competition.
The draft at the end of the season is based on your league. There will be 48 players and each team in your league will draft 3.