Blocks
Changed: Moved Soul Magma Blocks to the Natural Blocks tab in the creative inventory
Changed: Frosted, Elder, and Dragon Stems now also appear in the Natural Blocks tab in the creative inventory
Changed: All Nether stones (Elderrack, Draconite, Crimsonite, Netherwarp, Quarsite, Ironite, Monolite, Pyrirock, Zaronite, Soul Slate) now also appear in the Natural Blocks tab in the creative inventory
Plants
Changed: Frosted Fungi now grow into the Huge Frosted Fungus feature rather than a prebuilt structure
Changed: Elder Fungi now grow into the Huge Elder Fungus feature rather than a prebuilt structure
Changed: Dragon Fungi now grow into the Huge Dragon Fungus feature rather than a prebuilt structure
Changed: Icicle Reed patches generate less frequently
Changed: Rooted Snare patches generate less frequently
Changed: Rooted Snare patches contain less snares
Added Eldergrass
Retextured Frosted Fungus
Retextured Frosted Sprouts
Tools
Mobs
Changed: Revamped Shroomlets
Added the Burned (still a work in progress and cannot be spawned naturally yet)
Bugfixes
Fixed a potential issue where Icicle Reeds couldn't be placed in Overworld caves
Fixed an issue where Dragon Fungal Jungles could generate in Overworld caves
Fixed an issue where each lyreroot note would give a separate subtitle
Other
Changed: Completely reordered modded items in the creative inventory to match the organization of vanilla
Removed Herobrine

Nether Update Expanded is a vanilla+ mod, currently in Beta Testing, that adds to the Nether, with many new features being added.