Dear Ayanangshu Das It is a bit unclear what they mean with resubmit but if I understand the situation correctly then they mean:

-'Normally' you send the revised version (where you obviously did something with the suggestions made by the reviewers) and a separate document with your detailed response to the comments of the reviewers

-Sometimes the journal requires to highlight the changes you made in the original document

In the separate document you indicate for example:

-Reviewer 1 asked for the rational behind the choice to use (this and this) method. We added some explanation (see lines so and so in the manuscript)

-Reviewer 2 suggested to use another (let's say analyse) method. We did not follow this suggestion since (based on this and this study) this is a frequently used method and still considered state of the art

This is I think what they mean.

Best regards.

PS. The idea behind all this is that in this way the reviewers as well as the editor can see what the reviewers comments were and what you did with these recommendations etc.

In Geophysical Journal International, when the decision is revise and resubmit, you must log in to the submission system, go to your manuscript record, and select “Submit a revision” (not a new submission). This automatically links the revised version to the original manuscript ID. Upload both the revised manuscript and the response-to-reviewers file as separate docs, as requested by the editor