As far as instruction selection is concerned, all three appear to be same thing.
Support for these operands is experimental since AArch64 doesn't make use
of them and the in-tree targets that do use them (AMDGPU for
OperandWithDefaultOps, AMDGPU/ARM/Hexagon/Lanai for PredicateOperand, and ARM
for OperandWithDefaultOps) are not using tablegen-erated GlobalISel yet.