Why are there four ways of writing 黄? My keyboard does not allow me to input them all but I have found four (similar) ways in total of writing the Chinese character for yellow (黄). Why is this and how have these four forms come to differ?
黄

Simplifed variant (Unicode point U+9ec4)

黃

Traditional variant (Unicode point U+9ec3)

⿈

Kangxi radical 201 (Unicode point U+2fc8)



Variant character (Unicode point U+2155b)



Variant character (Unicode point U+28774)