Lionsgate

Italy Plaion has Dolby Vision, but the metadata is static: https://forum.blu-ray.com/showpost.php?p=22742198&postcount=92

Both 4K discs include a mono downmix instead of a proper stereo.

Original Lionsgate disc was encoded in incorrect colorspace and used a lossy->lossless transcode for the 5.1 mix.

US Lionsgate or International Universal 4K Blu-ray (similar encoding) - caps

Both come from a 4K scan of a 35mm film out which was made from the original 2K DI but the Lionsgate release has visible dust and damage marks while the Universal release is cleaned up more thoroughly. Both releases suffer from DNR which seems to have been baked into the DI. The colour grade is basically the same for both releases but the Lionsgate has Dolby Vision whereas the Universal is HDR10 only. The compression on the Lionsgate UHD base layer is apparently fine so the FEL doesn't make much of a difference.

The Lionsgate UHD has Dolby Atmos whereas the Universal UHD has DTS:X. Kick-ass was originally released with a 5.1 track which may be on the Universal Blu-ray.

The Lionsgate UHD is on a BD-100, the Universal UHD is on a BD-66.

The Universal UHD has no extras.

Lionsgate 4K Blu-ray has excessive DNR, Japan Blu-ray maybe better?

Lionsgate 4K Blu-ray disappointing, with burned in English subs

Lionsgate 4K Blu-ray has terrible compression, but still beats out the old disc which was sourced from a mediocre old scan with edge enhancement, and which has compression issues of its own.

The film originally premiered with two mixes, a 5.1 for upgraded theaters, and a distinct matrixed Dolby Stereo mix for older venues. The original 5.1 mix can only be found on the earliest LD/DVD releases, as all later releases replace it with a mediocre 7.1 mix with reduced dynamic range.

The Atmos mix is based off of the previous 7.1 remix, but with futher alterations as per director's wishes. One scene intentionally drops out into silence, see this post for details.