I consider them a pair. Twins if you will. Same formula, more or less, with an EP about a world. The transcendent features are lacking in both. Other worlds did not get swimmable water with IL and SE did not share snow depth, thundersnow weather, and arguably lifestyles.
Do not get me wrong. I like playing with lifestyles and think it has great potential as a feature, but it needs expanded. You can participate in the lifestyles everywhere, but more options would make sense in other places. For example, an adventurous lifestyle sees great benefits from a life in the SE world and the workaholic lifestyle benefits greatly from the new salaryman career. These lifestyles do not take as much advantage of other features as they should.
However, I like both SE and IL. I love the worlds, the BB, and most of the CAS. IL gave me some really nice off the grid play (though now it is completely intertwined with EL for me) and mermaids and SE gave me lifestyles and Japanese cultural details. Both are very important for my gameplay, so I enjoy them even if they could have been more.