Enhancements include screen-space shadows for fine details, improved parallax occlusion mapping (POM), and more realistic vegetation shading.
The remaster is generally more CPU-efficient than the original, better utilizing modern multi-core processors. System Requirements Crysis 3 Remastered [FLT]
The remaster demands significantly more modern hardware compared to the 2013 original: improved parallax occlusion mapping (POM)
Technical Overview: Crysis 3 Remastered