Calories are calories at the end of the day mate. HIIT in an ideal world is best for those hitting a plateau
Dat a bodyfat percentage that they want to lower. If someone did 45 mins of HIIT vs someone who did 45 mins of steady jog/walk then HIIT wins for calories burnt I imagine depending on intensity.
Here is an example of the two routes I could choose tomorrow which will burn the same amount of calories......
A) I am going to go for a 3 hour walk, wont get out of breath once and wont be taxing on my body or central nervous system. I have burnt a load of calories because of the amount of time I walked for.
B) Go to skinnypigs/or do some HIIT training at the gym for 45 minutes. I will be dripping in sweat and absolutely fucked! Will probably boot the cat out of the window when I get home from my session as my body has been taken to the limit and I just want to eat and go to bed!
Person A and B are likely to burn the same calories (probably person A even more). At the end of the day when I check my fitbit and see I have burnt say 3500 calories, my body doesnt know I have did HIIT, played footy, wanked into a flannel etc, it just knows I have burnt 3500 calories.
So to answer the question
@Frijj 
, calories burnt at the end of the day are exactly that. HIIT can create the burning of calories after your workout, whereas slow steady state will cease almost as soon as you stop, but when clock strikes midnight its what shows on your monitor/fitbit.