Here are some things we had gathered during Beta: https://wiki.unrealengine.com/UE3_to_UE4_Transition_Guide Feel free to edit and add things you find that are achieved differently in UE4.
You can do the lightmaps in Max/Maya just as well as you could do them in UE3, or in UE2. That workflow is advanced however and far from advised. There are lots of differences between the engine versions, and a lot of features are not yet in. Lensflares indeed, but also things like fog volumes. Also because the lighting…