I have been wondering what is the difference beetween being endorsed under Exceptional Talent or Exceptional Promise?!
I suggest the main point of difference between these two visas is related with duration of required stay in order to get Indefinite Leave to Remain (ILR).
Under Talent you have to stay for 3 years and under Promise - the full period, 5 years.
I have already discussed this question in my Tier 1 Exceptional Talent Visa Blog so, if you would like to read more details - read more at aseleznov.com