Not to be pedantic but the Global Entry status *should* get you TSA Pre and usually does but, for various reasons, it doesn't always seem to work (see the thread over on the SXM sub).

Getting Global Entry gets you a KTN (Known Traveler Number). You enter this number in your passenger profile when you book your flight/check in online. Having that number *should* get you TSA Pre check but you need to make sure you enter it (and if you have a code share trip where you are using multiple airlines, you need to make sure they all have it).

The relationship between Global Entry and TSA Pre seems either poorly implemented or more complicated than we know. It's very possible that they purposefully throw a bit of randomness in there to keep the bad guys guessing - who knows.

Tell ya what though, it's great when you get it.