Are aluminum frames different across the price range?

There are different types/series of "alloy". Different composition, heat treat, strength. Some are stronger but require heat treatment after they're welded and so on. So not all alloy/aluminum frame are equal.

A frame is built up from many different components.

A plain downtube might cost $25. An advanced one in a factory's catalog might cost $45 (tooling and engineering costs baked in). A custom one, hydroformed for this one specific model, might have its cost spread out over a run of 10000 frames to cost maybe $70 each, counting the engineering and design time behind it to fit the aesthetics and work for 4 different sizes.

A nice tapered bell-shaped head tube might cost $40, whereas a basic one might cost $20. The basic one needs precision machining to get the bores right and aligned. A non-aligned head tube, where the bottom hole might be off-center in relation to the upper one, might lead to weird creaking or clunking that's akin a loose headset, bad fork CSU, or loose fork bushings that shudder under braking at low speed. Heat from welding can warp the head tube as well, especially if it's a lightweight head tube and the welder did the entire weld around the fat downtube in sequence without allowing the tube to have the heat dissipated/sunk.

Some frame makers might opt to license some tech from current patent holders, like a straight off-set seat tube (from Knolly), to enable a short seat tube that accepts a long dropper. This is a cost that is passed to the consumer as part of the full price.

Chainstays are difficult to bend/shape to gain tire clearance, chainring clearance, chain slap clearance, cable routing, lateral bracing, pivot placement, etc. Doing all this creates a weak point that's prone to breakage. It's easy to throw extra mass to reinforce this area, with a thick plate of material, but brands put a lot of attention here to design in strength so extra material isn't needed.

How much does a quality hub cost? A quality handlebar? A quality seat post? Quality top tubes, seat stays, etc. aren't cheap either. Add up all the costs of the tubes, the precision machined bits like the head tube, BB, seat tube clamp area, pivot points, dropouts... a quality rocker, with bearings installed (quality ones that are $15-20 each), can cost over $250 by itself. A cheap rocker might cost like $100 for just two plates made of 7075 that bolt together, without bearings.


^ Over a dozen individual components make up a frame. Itemize them, at about $65 for each extensively machined dropouts and seat/chain stay yokes, $50 each for the head tube and BB shell, $30 each for the chain/seat stay tubes, $200 for the 3 main tubes... that's $680 for this frame, not considering the welding, coating, derailleur hanger, rear thru-axle, seat clamp, shipping, etc. A shop might charge $400+ for a CeraKote finish, for reference, if you demand a quality finish.

Jigs to make it easier to process a batch of these frames with consistent precision are quite expensive too, costing thousands or even tens of thousands. It's the wonder of Asian mass-production manufacturing efficiency that can get these frames to us at such competitive prices at this quality level, with so much value added on. I doubt they're getting rich at these prices, at least for the Banshee Paradox HT frame example, but merely just keeping the lights on and people continually employed.

Like another poster brought up, 6061 is less expensive than 6066 and 7005, which is less expensive than 6069. 7075 isn't easily welded, but is a far stronger alloy. 4130 Chromoly steel is a premium material that costs more too, but it's harder to shape, making it hard to come up with a unique aesthetic with it, to stand out from the competition.

"Production quality" is a term I expect to be more refined than "prototype" or "one-off custom". I place trust in such frames, and the experience the makers had from reiterating on their craft, to make something far more affordable than what I could've made myself. I feel spoiled by the choice. I personally can discern the differences between frames, even able to tell a lot from just looking, basing my judgement on my foundation of experience from riding many different frames myself. To someone without such experience, you perhaps just have to trust someone who does.

For example, it shouldn't be hard to see how cheap a Vitus Mythique's frame looks compared to a more expensive Specialized Stumpjumper's or a Banshee Titan's frame. You're getting an entire FS bike for the same asking price of a higher quality frame. The Vitus uses lower-cost catalog tubing (maybe from Astro Eng or Kinesis factory). Same can be said about getting an entire STA-TRU or WTB ST wheel for the cost of a single high end hub. Quality and precision costs more. Bikes made with less precision tend to have a cheap quirky feel.

I'll use 1990s GT frames as an example. The top self Zaskars used 7000 series and the mid range models used 6000 series aluminum tubing. If you put two polished frames side by side, you couldn't tell the difference besides subtle nuances that told you the 7000 series frames were made in California rather than Asia.

Some manufacturers develop a particular frame for key ride qualities. They might sell that frame across a range of price points, only changing the wheels and components as it increases in price. My '19 Specialized Chisel is a case, a ride quality and design you might not see on a lesser priced frame, say a Kinesis aluminum frame. So I think the answer is yes, there are better quality (or at least different) frames at higher price points.

Expensive aluminium frames are 0.5kg lighter than the cheap ones. Likely they will also look better (cheap frames will come with round tubes).

You can check the old specialized rockhopper vs stumpjumper to understand the differences (or any other brand who used to have standard and premium aluminium frames).
Don’t use the beginners frames as reference. They are overbuilt because some “beginners” bikes will be used for initiation to dirt jump and freeride. Brands don’t want those frames to brake constantly. During the early days of freeride, it was very common for specialized hardrocks owners to upgrade to a 130mm suspensions. At the time, 130mm was endure material.

A lot of major manufactures use identical aluminum frames throughout their lineup. So generally you will get the same frame from their cheapest to most expensive available in aluminum. Only the parts change,

Steve at Hardtail Party YouTube, has runs tests on lots of bikes with frames of different materials.
You can watch all of it on his videos.
Rear compliance can be a big contributor for comfort when you ride trails with rocks/roots. You can get beatup or not.
He recently said 5 frames were in the 90s out of 100. More around 60.
Material isn't the controlling factor. Design and construction are very important. Price is not a guarantee.