"Throathit" is a misnomer. It's not a specific thing, it's a blanket term used to describe any "discomfort in the throat" which may or may not be sought after. Many things can cause this and yield different types of discomfort in the throat. Things that can cause it are high nicotine, high PG, PGA, harsh dry hits, gremlins that make your atty not hit the way it's supposed to, etc. Types of "throat hit" could be: a deep wide thump to the lungs, a sharp acute sting in the throat on inhale (nothing on the exhale), a sharp acute sting in the throat on exhale (nothing on inhale) (I have experienced both of these independently), and different levels of general harshness.
PG gives a certain type of throathit, PGA gives it's own. Personally, I've not been able to find any amount of PGA in my DIYs that seems to do anything without making my vape taste like a nasty shot of liquor. To be fair, you can put the finest top shelf shot in front of me and it all tastes like gasoline (I wish I could enjoy it), so I definitely hate the taste of ethanol.