MiddleKick escribió: 

Firstly, it should be noted that there are in fact two versions of the game for the Dreamcast.
The first release which came out in '99 in Japan, and then later worldwide, is the game which most of us in the west are familiar with. The second version - Street Fighter Zero 3 Saikyo Ryu Dojo for Matching Service, was only available in Japan. In terms of game-play, this version featured a significant change: the removal of crouch-cancelling.


Dreamcast Street Fighter Alpha 3 (first version) changes

General:

- Significantly reduced invincibility of VCs at start-up
- Different movement of shadows compared to the arcade game, and as such allows many DC-exclusive shadow hit VCs in VC2 and VC3
- "Inflation" during VCs removed

Gouki:
Different timing for OTG VC

Dhalsim:
Slower far standing Strong, far standing Fierce and far standing Roundhouse
Hit box for close standing Strong altered; will trade a lot more often against jump-ins

Zangief:
Kattobi VC behaves differently - less distance travelled
"Glitch-driver" VC removed

Rose:
Level 3 Aura Soul Spark can be rolled away from before the damaging throw part can connect. May also be true of the Level 2 version.

Chun Li:
Different hit box for crouching Roundhouse - will trade a lot more.
Less invincibility on Level 3 Senretsu Kyaku

Cody:
Akuma's air fireball freezing bug removed.
Jab Criminal Upper behaves differently, so his corner trap/pressure game is greatly weakened

Karin:
Commands after her 360+K during a VC are now performed in the direction Karin faces after the move - as opposed to the direction she was facing before the move, like the arcade version.

I am willing to bet that there are a lot more severe changes to this version. The above information is based on observations of the glaringly obvious stuff many, many years ago.