what should I know that's importantly different
Welcome to the forum.
There are many differences some of which can cause confusion for those who are used to flying DJI products.
The ST16 is always Home no matter where you move during the flight. If you select Home, the H will fly back and land 10-15' from the controller. It does not record the takeoff location.
The H is also sensitive to initial GPS data. During the first flight of the day it's a good practice to allow the H to sit with the motors off until the almanac data has been downloaded. That can take several minutes. Don't start the motors until you have at least 15 sats on the display for a first flight. While you are waiting open Hardware Monitor and check the sticks to make sure they respond full scale and are not sluggish. Then check all the switch positions. Look at the battery a second time to make certain it is flush with the H. If it's not flush, it's not locked in.
Unless you travel hundreds of miles, it's not necessary to calibrate the compass after the initial calibration. Avoid flying anywhere near large metal structures. Remove the props and camera before doing a compass calibration.
The green arrow on the display shows you which way to move the right stick to bring the H home. When the arrow is pointing up, the nose is facing you.
The control distance of the H is much further than the video feed distance. The H is designed as a VLOS machine for photography and videography.
The batteries are not "Smart". That keeps the cost about 1/2 of Smart batts. They will not discharge on their own. If you land when the voltage is about 14.5 to 14.7 volts, the batteries will rebound to 15.2 v which is perfect for storage. Plan your flights so you are not a long distance away when the voltage has dropped to 15 v. Never fly to the first battery warning which is 14.3.
There are very few NFZ's built into the firmware all of which are major airports. They cannot be disabled in the field. You are the pilot and you are responsible for knowing where you can and cannot fly. If you fly commercially you can get unrestricted firmware from Yuneec.
Spend some time reading the Typhoon H "How to" section of this forum. Good info there.
Preflight Checks on the Typhoon H:
Props are locked
Battery is locked and flush with the H
Battery voltage on the display is 16.3 or higher
Sat count on the H is at least 15, on the ST-16, 7 or more
Switches in the correct position
Open Hardware Monitor and test the sticks
Stand 30' away from the aircraft
Take off full throttle to 15', then test sticks.
Land when the battery voltage reads 14.5 to 14.7v
If this is your first flight remove the camera until you can fly it well.