They are not the same thing
Authors often ask for an editor, get one, and come away disappointed — because they wanted someone to tell them whether the book works, and what they bought was someone to fix the commas.
There are three jobs. They happen in order, and doing them out of order wastes money.
Developmental editing — is the book working?
This looks at the book as a whole. Does the opening earn the reader's attention? Does the middle sag? Does the ending pay off what the beginning promised? Is the argument in your non-fiction actually made, or only asserted?
A developmental editor may tell you to cut a character, move chapter nine to chapter two, or write thirty pages that do not yet exist. It is the most useful and the most uncomfortable stage.
It comes first, because there is no point perfecting the punctuation of a chapter you are going to delete.
Copy editing — is every sentence doing its job?
Line by line. Clarity, repetition, rhythm, word choice, and consistency of voice. A copy editor will notice that you have used the word 'suddenly' forty times, that your narrator's register shifts in chapter eleven, and that the same character is warm on one page and cold on the next with nothing in between.
This is also where factual consistency gets caught — a character's eyes changing colour, a timeline that does not add up, a town that is two hours away in chapter three and twenty minutes away in chapter twelve.
Proofreading — is anything wrong?
The last pass, done on the typeset pages rather than the manuscript. Spelling, grammar, punctuation, and the mechanical things that only appear once the book is laid out: a heading stranded at the foot of a page, a line of a paragraph alone at the top of the next, a page number gone missing.
A proofreader is not there to improve your sentences. If they are rewriting, you needed a copy editor and you are paying for it late.
What we charge
Development editing is sold by the session, at ₹1,000 each, because the work is a conversation rather than a word count.
Proofreading is ₹1,000 per 10,000 words. Both are included in every package.