Yeah while FRLG was the least different and most faithful of the first three remakes, all three of FRLG, HGSS, and ORAS are very much different experiences from their original games with a lot of changes. HGSS isn't quite as different as ORAS, but it still is much more different from GSC than FRLG was from RGB. In fact it's still nearly just as different from GSC as ORAS is from RSE.
HGSS and ORAS are pretty much the same in one regard, and that is that they basically fundamentally change the base experience to align it closer with the base games of their generation. HGSS is very much a Gen 4 game and changes the experience to be more like DPP. ORAS is very much a Gen 6 game and fundamentally changes the experience to be more like XY.
HGSS even changed several story beats from the original, like the Kimono Girls only being battled later, and all of them showing up at different points in the game. It also makes Ho-oh and Lugia mandatory encounters in the story, whereas they were completely optional in the original, as a means of more closely aligning HGSS with DPP. Suicune from Crystal is now relegated to a post-game quest that takes place in Kanto. A lot of added content is made to more closely mirror Platinum, like the Gym Leader rematches, the Pokeathlon basically being Johto's own equivalent to Sinnoh's Contests, and so on and so forth. HGSS even attempts to tie itself to Sinnoh with the Arceus event at Sinjoh, and Crasher Wake appearing at one point. Much like how ORAS made its story and world connect to XY and Kalos.
HGSS is a nearly completely different experience from the original GSC in many regards. While the level curve is still pretty bad, it was changed a lot in several aspects, especially in the Kanto segment.
The only "remake" that truly falls into the glorified port territory is BDSP, which is so aggressively faithful that there is practically 0 change in the base experience from the original Diamond and Pearl in every front with a few gameplay mechanics like EXP All sloppily implemented, and practically zero new added content in the base experience. The game doesn't even look like Sword and Shield. Unlike the first three remakes, BDSP is still very much a Gen 4 game with a sloppy coat of paint added onto it.
Legends: Arceus is basically the "Sinnoh in the Sword and Shield" engine and the game that actually brings a new experience in the Gen 8 artstyle and engine, and takes being different that HGSS and ORAS worked towards to an even bigger step by being a completely different game in a different time period in that region. Legends games seem to be the way forward, with the next one being Legends: Z-A taking place in Kalos itself, presumably in the Scarlet and Violet engine.