A college basketball game at MSG will be a very different experience than a professional hockey game at the Prudential or Barclays arenas. But they'll probably all be fun, and interesting cultural experiences for someone from outside the US.
Note that college basketball is technically amateur (the players don't get paid in cash, although most get free tuition at the college) but is still a very big deal, particularly with schools like Villanova and St. John's that have historically strong basketball teams (Villanova won the most recent national championship). That game is likely to be attended mainly by alumni of the two schools. Since both schools are driving distance from NYC, there will likely be lots of fans for both teams. College teams also usually bring their own student pep bands and cheerleaders and a rowdy student cheering section to big basketball games.
The Islanders and Devils are both NHL teams, representing the highest level of professional ice hockey. The teams they're playing on those particular days aren't particularly close, so the vast majority of fans are likely to be supporters of the home team. The entertainment when play is stopped is likely to be a notch more commercial than at the basketball game (although there will be plenty of commercialism at both).