The difference is one comes with a DVD bonus disc in white sleeve which contains 55 minutes.
However what is interesting is here is what I translate from the product pages. THE TOP PORTION IS THE EXTRAS ON THE BLU-RAY DISC .... and most the DVD stuff is already on the Blu-ray. And it appears almost if not all are already on the Blu-ray EXTRAS OF USA therefore I dont think there is really any true exclusive Japan content. From what I gather........
<Blu-ray video bonus> (total of about 126 minutes)
★ Universe mode (reproduction mode with unfinished video)
● Spider · Ham's calamity
★ We are Spider-Man
★ Spider Bath: Animation in a new dimension
● Ultimate cast
★ Character design: Heroes and Hams
★ Characters: Designs: Roosters and Scorpions
● Great Creators: Stan Lee and Steve Ditko
● Find the loaded stuff
● Lyric Video (2 types)
-Newly created "Spider-Man" birth
<DVD video benefits> (total of about 55 minutes)
● Spider・ Ham's calamity
● The ultimate cast
● Great creators: Stan Lee and Steve Ditko
● Search for loaded material
● Lyric video (2 types)
● The new "Spider-Man" birth
USA supplements:
Spider-Man: Into The Spider-verse Ultra HD Blu-ray 4K Review | Hi-Def Ninja - Blu-ray SteelBooks - Pop Culture - Movie News
SUPPLEMENTS:
The Ultra HD Blu-ray 4K disc includes the following extras:
Audio Commentary (with Phil Lord, Christopher Miller, Bob Persichetti, Peter Ramsey, and Rodney Rothman)
Spider-Ham: Caught in a Ham animated short (4:01)
Spider-Man: Far From Home trailer (2:37)
MIB International trailer (2:37)
The blu-ray includes the following extras:
Audio Commentary (with Phil Lord, Christopher Miller, Bob Persichetti, Peter Ramsey, and Rodney Rothman)
Alternate Universe Mode viewing option (143:31)
A Tribute to Stan Lee and Steve Ditko (8:34)
The Spider-Verse Super Fan Easter Egg Challenge (5:02)
Post Malone & Swae Lee’s Sunflower music video (2:48)
Spider-Ham: Caught in a Ham animated short (4:01)
We Are Spider-Man (7:51)
Spider-Verse: A New Dimension (5:09)
The Ultimate Comics Cast (15:02)
Designing Cinematic Comic Book Characters: Heroes & Hams (7:45)
Designing Cinematic Comic Book Characters: Scoundrels & Scorpions (5:11)
Nicki Minaj, Anuela AA & Bantu’s Familia music video (3:00)
Spider-Man: Far From Home trailer (2:37)
MIB International trailer (2:37)