I think if you were to join a knowledgible fan for a few games and they were to "tune you in" as to what was going on, you might, just might, enjoy it a bit more.
As in rugby, it would take a season of football to learn the majority of of the game. For instance, take what goes on with the changes in teams. Just as one might change a defensive formation in rugby depending on many factors, the same occurs in NFL games. Add to that the fact that players of different abilities can be substituted on each play. Add to that the fact that the offense can do the same. This is what I mean when I say it is a game of chess.
Finally, in this brief discussion, add the two most fundamental and most important differences, those being forward passing of the ball and blocking an opponent from contacting the ball carrier. Forward pass = razzle dazzle excitement. Blocking = high speed violence.
I believe, overall, blocking is by far the biggest physical difference. It is out-and-out physical domination at a very personal level. Whilst scrum, ruck, and maul are team against team, blocking is one-on-one.
BTW... our rugby and footy coverage here sucks. Squash coverage sucks (of course, it's all blue dot and blue dot just plains sucks anyway). Cricket is limited to a half hour a week of highlights. At least we get two live Premiership games a week during the height of the season.