Here are the size charts for both kinds of cuts:
HPS stands for “high point of shoulder”. It’s the measurement that goes from the highest point of your shoulder straight down to the hem at the bottom of the t-shirt. The Bust 1″ BLW AMHL measurement is the one that runs from side to side, across the bust area- 1″, down from the bottom of the arm hole if the t-shirt is laying flat. The third measurement is the outside edge of the sleeve. In trying to decide which size to order, you may consider measuring one of your favorite t-shirts to see which size would be the most comparable.