I'm aware of the main differences table. However, I'm surprised the Pro-only features are not marked as such on the pdf manual (or the online one, unless I'm mistaken). Is there another place where more details are given ?
Are the items on the differences table exhaustive chapter heads ? Or are there other details, not fitting within those items, which are different ?
Also, when changelogs are announced, is there a way to know which changes might be Pro-only ?
The table is the only summary of differences.
The Light version is a lot more simple, and for people who want something more simple which costs less.
The manual covers everything in both Pro and Light, but most of the things in Light shouldn't need much explanation, other than the exact meaning of Preferences settings and things like that, which can be looked up in the manual when needed.
The manual is written with Pro in mind, since we don't have the resources to write a separate manual for Light, and we don't think it really needs one (given the simplicity, price, and how rare extensive documentation is these days in general). That's part of what makes Light cost less. We mention differences in some places of the manual, but documenting Pro is the focus, not documenting Light.
Release notes apply to both versions, although enhancements to some features may not be relevant to Light if they aren't enabled in the Light version.
During the initial evaluation period, you can switch between Pro and Light as many times as you want in order to compare the two versions and work out which is right for you. If you care about this level of detail, and don't just want a better file manager than File Explorer for occasional use, then Pro is probably what you want.
Thank you for your answer. To me, half the value of any program is its documentation, and generally speaking the help available. This is what makes Dopus so interesting : first it has a 1 000 pages + pdf manual (this is essential in my opinion, a book is infinitely more readable and intelligent than the equivalent information online), plus the body of added resources online is extremely strong.
One of the most valuable characteristics of Dopus documentation (in a broad sense) is it does not only explain how to apply features, it goes to great lengths explaining the concepts of the program, and why you would want to use them.
I'm all the more surprised that the manual (pdf or online) does not include the simple trick adopted by other publishers, of a small logo (or similar signal) to mark the Pro-only features. A different manual for the Light version is not needed, indeed it's more appropriate to have a unique one, precisely to better understand where the limit lays.
As a matter of fact, I have attempted to do just that, annotating my own pdf copy to mark the differences -- I extensively annotate my software manuals anyway.
There's another way to do it. The one adopted by PDF X-Change Editor, one of my most beloved programs (which also has an extensive help system). This program is even more complex in that respect, since it has three levels instead of two : free, intermediate (paid) and advanced (paid).
When you're in the free version (which is all I need), you can display the paid features, to understand the added benefit. But they are marked as such in the menus, so you're not trapped into starting a process, and discovering only at the end you cannot achieve it.
You can even test some of them, however you are warned that if you then save the modified document, it will have a watermark (this is specific to a pdf editor, of course).
But once you have kicked the tyres and understood the limits, you can elect to make the paid features disappear from the menus.
This is very clever, because it encourages you to upgrade if you need it, while it does not annoy you with hints if you don't.
I don't agree that most things in the Light edition do not need an explanation. I've been using it for years, and yet it's only recently I discovered you could copy or move with a single click from source to destination. This is a fundamental, original and extremely useful concept of the program, and as anything which changes ingrained habits, it needs to be taught and learned.
I'm also surprised you seem to consider the Light version as a... lightweight program. I consider myself an advanced user (my whole career has been devoted to helping people use their computers and software), but I still have not scratched the surface of Light (I think).
My understanding of the limit between Light and Pro is the following : there is one feature of Pro which is not meant for advanced users, Explorer replacement. This is so convenient for everybody, that it's really an incitement to go Pro. On the other hand, if you cannot afford it, you can just launch the program manually, and its power is still available to you. This is a clever way to draw the limit.
However (again to the best of my understanding), all the other Pro exclusive features are really for advanced users : editing metadata, FTP, duplicate file finder, floating toolbars, system-wide hotkeys, customize commands and context menus (although it seems you cannot customize toolbars either without the Pro edition, since you need commands to customize them with anyway) ; and scripting.
My personal needs for Pro might only lay in the customizing department (and I'm not quite sure of the limit here), and possibly in editing metadata (again, not sure exactly what is out of bonds with Light). Scripting ? Nice to have, if I can use ready-made scripts (and that's one of the very appealing benefits of the help system). But I'm quite sure I won't write my own.
Go Pro!
You know you want it.
The only regret you'll have is that you waited so long to get it 
A proper manual is just another feature Pro has over Light