What's the difference between LookupTable and LookupTableTransform?

LookupTable:

Class for efficiently approximating expensive arithmetic operations.

The approximation is based on linear interpolation between pre-calculated values. The approximated function should be passed as a callable object to the constructor along with the number of data points to be pre-calculated. The accuracy of the approximation can be increased by using more points at the cost of a larger memory footprint.

Consider using LookupTableTransform as an easy-to-use alternative.

LookupTableTransform:

Class for approximating expensive arithmetic operations.

Once initialised, this class can be used just like the function it approximates via operator().

Why should I consider LookupTableTransform as an alternative? What does it do better?