Pitman follows tongue placement very well, both height and front/back. Front vowels are dots. Back vowels are dashes. Low vowels are 1st position (written low), middle are written middle, and low vowels are written high. (Why did he flip them?) Heavy/light alternates on the way down. The most common shortcuts or poor penmanship will result in a similar-sounding word.
This is no surprise. Isaac Pitman was enthusiastic about phonetics and spelling reform.
Gregg follows front/back placement, with circles in the front and hooks in the back, but follows English spelling rather than tongue height. Anniversary Gregg has optional vowel diacriticals to help distinguish vowels. Again, the diacriticals follow English spelling rather than tongue placement. The two back vowels with dashes are rounded. All but the E series use dash for highest, dot for middle, and nothing for lowest.
Gregg diphthongs are accurately identified and broken into their component parts.
The example words are taken from the textbooks, not my Canadian-trained tongue. Both systems put U (luck) to the back, rather than the middle as in the IPA chart. The chart I used didn’t discuss rounded or not rounded. I forgot to label top/bottom tongue positions. It’s as written. Beet is high, bat is low.