I can not answer that question with certainty, but from what I have seen there is no difference which would justify playing it without the DLC if you already have bought it.
The point of the game is kept even when jumping between versions (see below) and there are no differences which I have spotted (but the DLC do list a lot of enhancements - but nothing I would like to avoid by playing without the DLC).
Even on the contrary - concerning Linux it is now a 64 bit binary working out of the box on Ubuntu 18.04 LTS, Eoan 19.10 and Focal 20.04 LTS, while the old in development Demo on itch.io and the GOG version without DLC are 32 bit only and need a little work (as described in my post "Demo version, missing 32 bit libs and DLC with 64 bit binary").
So I would only recommend to play the game incl. DLC (for those who have bought the DLC).
But if you really want to get the impression yourself: just download it from the webpage
https://www.gog.com/account as there are two separate install scripts for the base game and the DLC - so installing the base game in two different directories and only installing the DLC to one of them is easy - so you can switch (I do it as a habit - but till that day I never saw a reason of playing a version without DLCs - but I avoid those which are known to bring in bugs annoying gamers ...).
I have the problem that I will not use Galaxy as I don't want these functions (one of the reasons I am not using Steam - and will not in future) and don't get the development version via the Download page ... which would be nice if that will change in near future.
But thus I don't know about a possible workaround with Galaxy to install the base game only.
If one wants it one may purchase the base game first and install it - then copying the install directory - and later purchase the DLC and install it ... that should work also with Galaxy (renaming directories etc.).
Hope this helps.