In international football you have 10 games a season, with players from different clubs. There's no time for proper coaching; they're just recovering from playing on the Saturday.
The biggest thing I've found since I left the game - and I'm glad I chose to leave rather than being sacked - is that so many people are in football for the wrong reasons. Not because they love the game, but because they smell money.
In club football you have your players and staff with you all the time, preparing for two games a week, you know them inside out, you have a discipline over them.