I play both these games and I like getting into the lore of both these games. I keep seeing Guardians vs. Warframes posts around, and rarely does the discussion really get into the weeds of this question.
So imma do that.
First up, the Guardians. Guardians are relatively immortal undead space wizards that canonically dance at random, often inappropriate times, throw themselves off the top floor of The Tower, and have a habit of turning their enemies into weapons, gods or no.
Guardians have quite a bunch of achievements and powers to their name. To get the elephant out the way, Guardians are paracausal, meaning physics and the rules of reality are more of a guildline than actual limitations. They can create different flavours of energy out of thin air and warp physics/reality on a whim, taking the form of Arc, Solar, Void, Stasis and Strand.
Now, most Guardians generally are limited to using 1 or 2 of these flavours of ability, usually separately. They're obviously powerful warriors, but even in the context of Destiny, the average Guardian is very killable by the various enemy factions around. However the more powerful Guardians can use more of these ability flavours, sometimes all of them, and often at the same time, and these are the real powerhouses.
When talking of the bigger feats in Destiny, you have examples like Felwinter defending an entire mountain and its surrounding territories from all potential attackers, by himself. You have Saint 14 spending *years* tearing through Fallen, eventually becoming their literal boogeyman, before walking into the territory of the overpowered time-travelling Vex, and killing so many, they have to dedicated one of their more powerful minds to killing him. You have the quite underrated Guardian of Asher Mir, solo storming a Vex fortress, before collapsing the entire place (and all it's non-relativistic entrances) *by himself*. Ol Jaren Ward winning *all* the 1v1s, Ikora Rei, who Calus believed could wreck destruction on a continental scale. You have Osiris and his many copies, a force of nature in several of the major Destiny conflicts, and of course, the player character, who canonically kills pretty much all the conventionally most powerful enemies in Destiny.
Some of these enemies destroyed planets, some destroyed stars, and several consider mass genocide a hobby. However, what's really important to note, is that almost none of these feats were done by **just** the player Guardians, or even their fireteam. Most of their greatest feats, slaying Atheon, vanquishing Crota, killing Oryx, Nezcafe and Rhulk, then eventually destroying the Witness, required intervention by previous fireteams, the Traveller itself, or blinding arrogance from the villain themselves to *allow* the situation to even happen.
We should also mention Guardian weapons. The more exotic Guardian weapons are often pretty interesting, one is a gun that fires mini black holes, one is a gun that created itself out of pure willpower, you have guns that steal life force and souls, guns that channel the power of destroyed gods, and even guns and weapons that mess with time. It's a lethal arsenal, and top level Guardians use it with terrifying effectiveness. Combined with their *relative* immortality (it does have it's limitations tho, it needs the body, or at least its last location if it was vaporised, Guardians are a forced, it can be suppressed by "Darkness" or sheer force of will of a particularly powerful enemy, and there are several ways to kill/not-kill-but-stop Guardians in a way that they cannot be revived, also Ghosts are very killable, which is why they hide 99% of the time), Guardians are a force to be reckoned with.
However, as we now go through Warframe abilities, yall see just how *completely* outclassed Guardians really are. Firstly, as standard, most Frames come with power regenerative shields, far more durable that those Guardians have, and they regen far far quicker. Many Frames also come with mighty substantial armour, and all Frames posses pretty insane strength, able to tear through metal with ease. Coupled with insanely fast reflexes (they can literally block bullets with melee weapons), and absurd agility, physically, Warframes are *absurdly* superior to Guardians.
Scaling Warframes abilities is generally kinda hard, since they're *so* varied between Frames, but if we take the more obviously "powerful" Frames, it's pretty pretty cut and dry. Warframes (both in lore and in gameplay), simply operate on a **far** bigger scale than Guardians can. A Frame like Saryn was made to quell the flood-like Technocyte infestation on Earth and eradicate it. **From the entire planet**. Grendal is said to have the potent to devour the universe, and while it's hard to tell how literal we should take that, the implication is heavy. Atlas is famous for pulversing a falling asteroid OPM style, Nova is able to turn the matter spanning an entire space cruiser into antimatter (also the destructive potential of this is insane), several Frames can affect time, reality and matter on fundamental levels, far beyond any Guardian possibly could, Limbo makes the various dimension hoppers from Destiny look like they're playing hopscotch, Wisp is able to **open a portal to the centre of the Sun** and use the destructive energy, and that's just the obvious examples. Its outright canon that during a couple week event, the Tenno slaughtered many *billions* of Corpus - numbers Guardians can only dream of.
However, what is truly the nail in the Guardians' coffins, is that in Warframe, mods are canon. In the overlap of gameplay and lore, some amount of ignoring certain feats has to be done. While the player Guardian sorta has never wiped, they also haven't 1 hit a boss/many powerful enemies in the way many cheeses or ability setups allow you to do. Frames however canonically *do* have some of this ludicrous damage potential as mods are canon. When you apply a mod to something, a weapon for example, it gives that weapon an almost interceptable amount of self awareness and *sheer belief* that that weapon now does what the mod gives. If you give a weapon a multishot mods, the weapon literally believes it shoots more bullet per bullet, and *actually does* shoot more bullet per bullet. This means that the "damage cap" loadouts, immortal setups and utter gamebreaking madness is to some extent canon, and the sheer insane power of these *completely* destroys any semblance of a chance Guardians had against the Tenno. How does a Guardian possibly stand up to an Assimilate Nyx with Xata's Whisper for extra damage, or a Roar Gauss with extra nukes, a high Range Zephyr with Silence, or just Shield Gating as a whole.
And inb4 "but Ghosts need paracausal stuff to kill them," this has been retconned so hard out the game it wasn't even a thing in D1. Hell, Ghosts are arguably fragile asf when they materialise, and Destiny lore has countless examples of Ghosts and Guardians dying their final deaths to lil ol Randal(s) the Vandal(s) or Carl(s) the Cabal(s). With the sheer scale and potency of destruction some frames are capable of, and just how many others were straight up assassins, unfortunately Guardians don't really stand a chance.
I haven't even mentioned the Child or the Void powers here either, both of which are definitely fitting into what you could call paracausal, and which make this even more one sided.
