A manufacturer's appliance range usually looks like a ladder of quality. Most of the ladder is built on a single chassis, with differences that are not always where buyers assume.
One platform, many badges
Developing a washing machine or a dishwasher is expensive, so the same drum, tub, frame and pump are reused across many models in a range.
What changes between them is the control board, the programme list, the door finish, the insulation and occasionally the motor, rather than the underlying structure.
That reuse is why models look alike inside and why the same spare parts fit across several price points within one brand's family.
Where the money actually goes
Higher models often spend their extra cost on features that are noticeable in a showroom, such as displays, programme counts, lighting and quieter operation.
Components that determine working life, principally the motor, the bearings, the pump and the electronics, may be shared with cheaper versions of the same platform.
The exception is the noise rating, since reducing it requires genuine additional material in insulation and mounting, and that improvement is real and measurable.
Why retailer-exclusive models exist
Manufacturers produce variants for individual chains with distinct model numbers, which prevents the identical product being price-checked against a competitor.
The variant may differ only in a colour, a badge or one programme, but the number is different, so no comparison site can line the two up directly.
Comparing on specification rather than on model name is what defeats this, since capacity, energy class, spin speed and noise are stated in comparable terms.
What the energy label does and does not tell you
Energy labels are measured on a defined test programme, which is not necessarily the programme most households use for most of their loads.
The figures are comparable between machines because everyone is tested the same way, but they underestimate real consumption where the test programme is rarely selected.
Water use, noise and capacity on the same label are more directly transferable, since they depend less on which cycle a household actually runs.
The question worth asking before buying
Repairability drives long-run cost more than purchase price, so parts availability, the cost of a common failure and access to service matter considerably.
Brands vary widely in how long they supply parts and how easily a machine can be opened, and that information is harder to find than any specification.
Where two models share a platform, the cheaper one often represents the same working life with fewer features, which is a different trade from lower quality.