The main difference is what happens if
isLooping starts off as false.
With a standard while loop your code to generate the enemies will not be run, whereas using a do-while loop will ensure that the waves are always instantiated at least once.
If your intention is to always have infinitely repeating enemy waves, then you can take either approach and you won’t really see any difference. However, you may start to see problems if you only want your waves to play through once - for instance, if you want to create a set number of enemies for a given the level.
Towards the end of the lecture, I test my solution with
isLooping starting as either true or false so you can see the difference. If you run the same test using just a while-loop then you should witness the behaviour I mentioned above.
I hope that helps.