First off I play for fun and ratings second. However remember the formula is a complicated one. There are a variety of factors based on both you and your opponent. Number of games played, quality of oppostion, wins-loss-draw record is taken into account as well as your current opponent that you beat or lost to. It is impossible to compare why you gained or lost more points than your opponent or gained or lost less points than your opponent. Their game record is going to be different than yours based their own record and game history and opponent history. I look at ratings as an afterthought as I use it to find games against opposition in the same range as me or higher. However if you play for the fun of it the rating number means very little.