The same Lightroom preset can produce noticeably different results on a raw file and a JPEG. A JPEG already contains processing from the camera or another export. A raw file gives Lightroom sensor data to interpret through a profile and its editing controls. Identical adjustments therefore begin from different images.
This becomes obvious when you try a cinematic look on a pale raw landscape and an already contrasty JPEG. The JPEG may develop blocked shadows or strong color while the raw version still looks soft. Evaluate the photograph you have, with attention to what happened before the preset.
Find out what the file already contains
Start with the file type and editing history. A JPEG made in camera can include a picture style, white balance and sharpening. A JPEG exported from an editor can include an earlier grade as well. Applying a second look adds another set of decisions to that rendered result.
For raw files, look at the selected profile before changing sliders. Profiles affect the starting rendering. A preset may include a profile choice, or it may leave the existing one in place. Check which controls changed after applying it; each preset can include a different set of adjustments.
Use a fresh editing state for the first comparison, then test the preset against your normal workflow. Resetting an image in Lightroom does not undo the color and contrast already baked into a JPEG. It clears Lightroom's adjustments to that file.
Compare the same scene when you can
A raw and JPEG pair from the same exposure is useful for learning how the camera rendering changes the starting point. Compare matching crops under the same display conditions. Two unrelated photographs introduce differences in lighting, subject color and exposure that make the file-format comparison difficult to interpret.
Even a matching pair may have different starting brightness and color. First compare the unedited files. Notice the contrast in the sky and the separation between dark foliage. Then apply the same preset and inspect which differences grow. A stronger camera picture style may already have compressed the shadows the preset is trying to deepen.
If you are testing the free landscape and 3D render preset samples, use them as a starting look for each file. The sample pack does not remove the need to adjust the image. Its stated subjects are landscapes and 3D environment renders, and it is unsuitable for portraits.
Judge the resulting tones
Look at the histogram alongside the image. Dark areas losing separation may need less contrast, a different black point or a local adjustment. A bright sky with flat white patches needs inspection before more saturation. If detail is absent from the rendered file, moving a highlight slider cannot reliably recreate the missing scene information.
Raw files commonly allow more flexible tonal and white-balance adjustments than an already rendered JPEG, but latitude depends on the capture. A raw file can also contain clipped highlights or noisy shadows. Avoid treating the file extension as a promise that every mistake is recoverable.
Reduce the preset's strength when the application and preset support an amount control. Otherwise, examine the settings it changed and adjust the ones causing trouble. A preset might include a curve and color adjustments as well as basic sliders. Correcting only Exposure may leave a harsh curve or an unwanted color shift untouched.
White balance values need context
Raw and JPEG white-balance controls can use different ranges or representations. Matching a displayed temperature value does not ensure matching color. Compare a plausible neutral surface and the relationship between sunlit and shaded areas. Keep warm light when it belongs to the scene.
A cool shadow under trees and a warm sunlit path can coexist in the same photograph. Correcting both with one global change may remove that difference. Once the overall balance is credible, use a restrained local correction for a specific color problem. Check that the local adjustment does not leave an obvious boundary.
Choose a consistent working source
For a series, edit from the same kind of source when practical. Mixing raw originals with previously graded JPEG exports can require individual compensation. Keep the files clearly named and preserve originals so a later revision starts from the intended source.
When a series must include both formats, choose a reference image for the final appearance. Match brightness and color relationships by eye, with the images side by side. Equal slider settings are a useful starting experiment; the finished images may need different values.
Study how the sky, distant forms and foreground sit together in the Before the World Woke Up 3D environment artwork. Use those broad relationships as a reference when comparing your own edits. Check both files at full size before exporting, especially where bright sky meets a darker foreground.