What does a "major revision" mean?
In my field (chemistry), the practice is: for those journals that make a clear distinction between minor and major revision requests, “major revision” means that the paper will have to undergo further review after revision, usually by the same referees, while “minor revision” means that while changes should be made, no further reviewing is needed.

Not all journals make this distinction, however: for some, the need for further reviewing will be decided by the editor upon reading your response to the reviewers’ comments.



For example, here are screenshots of the web interface facing the reviewer of ACS and RSC journals when he has to fill in his review. You can see that the categories are different for different journals.

Example 1:



Example 2: