They are very, very different in terms of implementation given that Cruyff and Van Gaal have very different ideologies when it comes to totaalveotbal.
Wut? Sorry but I feel compelled to post this emoticon for the first time:
2008/ 2009: Barcelona had the best defensive record in the entire league, and conceded 1 goal per game in Europe.
2009/ 2010: Barcelona had the best defensive record in the entire league, and conceded 0.83 goals per game in Europe.
2010/ 2011: Barcelona had the best defensive record in the entire league, and conceded 0.75 goals per game in Europe.
2011/ 2012: Barcelona had the 2nd best defensive record in the entire league, and conceded 0.83 goals per game in Europe.
2013/ 2014: Bayern Munich had the best defensive record in the entire league, and conceded 1.08 goals per game in Europe.
2014/ 2015: Bayern Munich had the best defensive record in the entire league, and conceded 1.08 goals per game in Europe.
2015/ 2016: Bayern Munich have the best defensive record in the entire league, and have conceded 0.75 goals per game in Europe.
United is currently conceding 1 goal per game in Europe. The caveat here is that for Europe, Guadriola's stats include latter stages of the competition (semi-finals and onwards - vs Barcelona, Real Madrid, Internazionale which inflate the numbers because he never finished outside of the Top 4 in Europe), meaning much stronger opposition in the deep end of the competition. Barring anomalies, that's a brilliant defensive record for a coach that employs very attacking tactics as opposed to setting up in a cagey manner.