Point two cameras at the same subject under the same light and the two files will not match. The difference is not a fault; it is a series of deliberate manufacturer choices.
Sensors record numbers, not colours
A sensor measures light through a grid of red, green and blue filters. Those filters have different transmission curves between manufacturers, so the raw numbers differ before any processing occurs.
Converting those numbers into colours requires a matrix of assumptions about how the filters respond and how the result should look. That conversion is proprietary and is where houses diverge.
The consequence is that no two bodies agree on what a particular red is, and the disagreement is largest exactly where it is most visible, in skin tones and saturated fabrics.
White balance is an interpretation
Automatic white balance guesses which part of the frame should be neutral and shifts everything else accordingly. That guess depends on scene content, so a wide shot and a close-up can land differently.
Manufacturers also tune the guess to taste. One will lean warm to flatter faces, another will hold closer to a technical neutral, and a third will preserve some of the ambient cast deliberately.
Setting a fixed value on both bodies removes the guessing but not the difference, because the same numeric temperature still passes through two different colour matrices.
Picture profiles change the shape of the image
A default profile applies contrast, saturation and sharpening before the file is written. Those curves are baked in and cannot be reliably undone later without visible damage.
Flat or log profiles postpone the decision by recording a low-contrast image that expects grading. Two log profiles from different makers are still not interchangeable; they map tones differently.
Matching therefore has to happen in grading rather than in the menu, using one camera as the reference and moving the other toward it deliberately.
Lenses shift the result again
Coatings vary in how much they transmit at each wavelength, so the same body with two lenses produces slightly different colour and contrast, particularly against backlight.
Older glass often renders warmer and with lower contrast, which is why a mixed lens kit can undo the careful matching of two identical bodies.
The practical route to a match
Shooting a reference card at the head of every setup gives a fixed point to align to. It costs seconds on set and removes most of the guesswork from the grade.
Locking exposure, white balance and profile manually on both bodies prevents the cameras from drifting apart mid-scene, which is far harder to repair than a constant offset.
Where a perfect match is impossible, consistency within a scene matters more than consistency across a project. Viewers notice a change at a cut, not a difference between reels.