嫉妒jídù:因人胜过自己而产生的忌恨心理hate someone because he/she is better than you
忌妒jìdù:对胜过自己的人心怀怨恨 hate someone that is better/more skilled than you
妒忌dùjì:对别人的长处感到不痛快或忿恨,同时又希望自己具有同样长处 feel unhappy about or hate that someone doing better or more skilled than you,but at the same time wishing to skilled or good as him/her
Btw,嫉妒 is a noun,妒忌 and 忌妒 are verbs.But basically you don't really have to care about the difference btw these words in daily use as they are interchangeable and the biggest difference is just...the pronunciation :p
Hope this helps x