In ThumbEE state, the processor uses almost the same instruction set as Thumb-2 although some instructions behave differently, and a few are removed, or added.
The key differences are:
additional state changing instructions in both Thumb state and ThumbEE state
new instructions to branch to handlers
null pointer checking on loads and stores
an additional instruction in ThumbEE state to check array bounds
some other modifications to the load, store, and branch instructions.
ThumbEE instructions are accessible when the processor is in ThumbEE state.