When a casual game is Updated, what does the update usually include?

It depends upon the update. Some updates address glitches that some but not all players have experienced; some updates are more critical in that most players have experienced a problem. Sometimes an update just adds some tweaks to the game that are not essential at all. So, it all depends on the update. You can always go to the Big Fish forum of a game that has been updated and there will be a post by a moderator that explains exactly what any particular update is for.

Marian, Thank you.