What is the difference between minor, moderate, and major revisions?
I have never seen the term "moderate revision", only "minor revision".

The exact semantics of major or minor revisions will depend on the journal - at some journals, a minor revision will not be externally reviewed any more, while a major revision will. At others, the difference is less clear-cut and may simply reflect the editor's feeling of how many additional rounds of review may be necessary.

Similarly, the differences in the probabilities for acceptance between different types of revisions will vary between journals. At some journals, even a major revision is almost certain to be finally accepted, even if it may still take multiple rounds of review, barring rare cases.