The home team earns booster packs and money from ticket sales and concessions but you risk injury.

Use your reserves if you have a full 22 man squad.

The players don't lose any where near as much conditioning as they do when they play a league/champions league/cup game.

I haven't kept any data, but it looks like you gain just slightly more skill points if you train instead of play a game, but not much.

The visitors do not gain or lose booster packs, skill points or conditioning. Also, no injuries for the visitor.