Looks less drastic an overall difference than the IM ones. More detailed/realistic/misty water, a bit more atmosphere and fine-tuning in the background. A little harder to see what more work in texture/reflection et al there was done because it's so dark. There's no hard/fast rule as to what stage each production's FX work is in by the time they put out trailers. Logic and a little knowledge of post-scheduling presents the plausibility of temp/early versions of FX shots in trailers that start many months before theatrical release. But with both those examples...again....the differences in effects work weren't so night and day that it changes your impression of the movie from the time you see the trailer to the time you watch the movie. It's not like a lot of people said 'god, the water around that owl ship looks horrible..this movie's going to suck'.
Again, with the GL trailer, it wasn't really just the effects themselves that made it feel like 'just another superhero movie'. Maybe the composition of the shots looked a bit rudimentary, or maybe the really complex and epic sequences weren't ready...in any presentable stage...by the time they put out that first trailer. So...how different will they look in the final movie? Well, if we're using these examples as a measuring stuck...different, but probably not drastically as to be unrecognizable. So if that's where some folks are looking to gain some confidence after the first trailer, ultimately, it's probably better to look elsewhere as well as more trailers come out.