Really? You can do both editing and retouching in Photo Mechanic? That's something your copy allows you to do?
PM is not just limited to culling images as you stated, but can also edit them, in albeit in a extremely limited manner. Though less than I recall it having when I gave up on it a decade ago, I have to say. Probably the reason why I did move on, as for
my needs PM is slower to use, because it adds an extra and pointless stage to my workflow.
Amusing the wiki page on PM says - "
While Photo Mechanic has basic support for simple image edits, such as crops, it is meant to be used in concert with a dedicated photo editing program, such as Adobe Photoshop" - Notice how '
edit' is used.
And tellingly on PDN, PM is not even considered to be a photo editor - "
And unlike Lightroom and Aperture which keep adding editing functions, Photo Mechanic isn't really a photo editor at all. Sure, there are some very basic tools such as being able to rotate and crop images but these are almost afterthoughts." It's a Digital Asset Manager [DAM] application in their view.
Learning any trade is to learn its jargon first. At least for me, I haven't encountered any professional "retouching" firm calling itself an "editing" firm yet, and all the retouchers that I know haven't started to call themselves editors yet. At least from my own experience, all curators who I have interacted with well understand the precise difference between editing and retouching.
English is a wonderful language and we have a silly amount of words at our disposal, many with multiple meanings. One of the benefits of that is that there can be a whole range of subtleties of meaning with different words and amongst groups of people use the same words, such as in this case of editing where curators and photographers will correctly use the same word, albeit in slightly different ways. It's all about context. For example if I talk to a curator or a photographer about editing, I'm actually talking about different things depending to whom I am speaking.
As for retouching, it is usually used to mean altering images in ways beyond simple grading and it's a far more specialist skill, which is why you get places that specialise in retouching. Now if I was retouching an image I may not use the word editing as retouching involves more than a simple edit. Just like if I was running for a bus, I wouldn't say I was jogging for the bus, despite jogging being a type of running. However, I would do my retouching in a
photo editor like Photoshop.
Grading is yet another word for altering an image. One which is borrowed from the film industry where in film post processing, grading and timing are often used interchangeably. The reason being is that the time you developed film for, altered its look or grade. And as I work in film as well as stills I sometimes refer to tweaking my images as grading them, which is more about giving a specific overall look to a photo than say removing dust spots or darkening the sky, which would be editing. But if I was cloning out things, adding a third eye or making skin look like weird melted plastic, then I would say I was retouching.
Now at this point the folks who behave like religious zealots when it comes to languages changing will start stamping their feet and insist that grading is what you do to college essays and should not be used for altering the look of film or images.

Anyway I have some new photos that need some tweaking/post processing/grading/retouching/editing/altering/fine tuning/manipulating/photoshopping/developing.