Adult vs kid's bicycle for a tall kid?
You are correct that there isn't anything intrinsically different between bikes designed for preteens and adult bikes. Kids bikes tend to have lower end, inexpensive components and drivetrains with a single front chainring only.

A adult bike will come with multiple front chainrings and front derailleur and shifter, so your daughter will have to learn to use those as well as the rear gears, but that isn't particularly difficult. Less expensive mountain or hybrid bikes will come with a triple front crank, if you want to simplify gear shifting  to start with put the chain in the middle ring just shift the rear gears.

One concern would be the wheels may have quick releases instead of nuts on threaded axles, which might become unsecured with obvious bad consequences. The quick releases would have to be tightened enough so they couldn't be undone easily, and your daughter would have to know to not ride the bike if one or both come loose.