Remade= Redoing most of the things within the product to add/remove things in order to make it look new at modern standards. (example the final fantasy 7 remake)
Remaster= Updating something into moder standards to make it attractive for the public without making any major changes.(example GTA trilogy)
Refurbish= same as remaster but focused in improvement for better usage for the customer/user.
Remaster and Refurbish are the same exact thing on this medium, for any given reason, both positive and negative. it is about renovating, redecorating, whether to improve on existing assets, or to fit the Audiovisual standard of the moment. Say, a work was made in a time when not just the aspect ratio, but the max quality of screen resolution was too small for today, and a lot of assets have to be made to make use of that extra on-screen real estate. Modern remasters for games as old as the beginning of the last decade would instead focus on the now current modern artistic techniques, like ray-tracing for lighting (which, to date, is about as trendry as the old brown and bloom was in the mid-2000's) and other new mesh tricks that add extra depth without using that many polygons. Even if it adds one or two new things, maybe a dozen more, mainly QoL or a few new story events, the game is essentially still is the same game redressed to modern standards. Changing the entire artstyle of the game may not necessarily mean it is a remake, either. Remasters stay familiar.
Remakes go the extra mile or kilometer. They try to change gameplay, flow, the player perspective, even (optionally) the genre of the whole game, while telling the same story with new cutscene perspectives, or maybe even making those events part of the gameplay. The key factor can be explained as if saying "we are making the game for the first time all over again". Almost paradoxically. Examples are, as mentioned, Final Fantasy 7 Remake, but also Pokémon's Gen 8 remakes of Gen 1 and Gen 4. Or gen 6's remake of Gen 3. Even the simple act of going from 2D to 3D, or vice versa counts, as this means redoing almost every component of the game to fit the new direction. There are times when a remake could sometimes feel like a reboot, too! But not always. Remakes change the game radically enough to feel new again. This all also applies to the opposite direction: a "Demake".
Now, the term that I technically wanted to mention earlier was "Rebuild", which is probably not as popularized as marketable yet, but it is a coined term used plenty of times in other media. This is sorta like the middle ground of both concepts above. An entire redo of the engine (or an update to the same engine), artstyle, backend resources, while still keeping the entire game the same as what you might recall it in the original release. This is basically games such as Pokémon Gen 4's release of Gen 2, and Gen 3's release of Gen 2, but also games like the 2D-HD redos of Live A Live and the future Dragon Quest 3 release in that style. The Last of Us Part 1 also had this sort of treatment, if I recall correctly. Which pushes things a lot further than keeping the familiar style of its original release, but not too far that may make it unrecognizeable or too unique. Rebuilds can change games greatly enough to feel different, but generally familiar enough at the same time. This often fits the "2D to 3D and vice versa" example, too.
tl;dr This game mod in its current state fits the remaster bill, but it is on its way to be a "rebuild". It's gonna have a lot of new gameplay changes than just stat rebalancing, art shift, and animation changes. Major character gameplay interactions will be redone, bosses will eventually no longer be the same, and stages will eventually be reworked beyond just enemy wave and container rearrangements. Plus, everything after Stage 5 will pretty much be unique to RedEye and company's vision, even if it will still be based on Zeta's existing notes. The work put here is not so simple. And we have yet to fully see what is currently being cooked!