More characters,more character balance,colorful/detailed environments,and my favorite SF Alpha game.
Even though the original Street Fighter Alpha was an enjoyable SF game,it didn't have a big roster of characters,the characters were unbalanced(Ken and Ryu were way overpowered).
In Street Fighter Alpha 2,the damage from Ryu and Ken's hadoken and shoryuken have been reduced(they are still great characters to use,but don't have a HUGE advantage over enemies anymore).
The other characters have better AI now and the gameplay is faster.
Just like with many other Street Fighter games,Street Fighter Alpha 2 has the delicate timing for special moves and combos,and made positioning your character very important.An example is if you can connect with Ken or Ryu's shoryuken,it will do a lot of damage to enemies,if you miss it will leave you vulnerable and you can use the shoryuken to counter opponent's moves with(since it's the most powerful move).Or you can use the hadoken(energy ball projectiles)to keep your opponent tied down or if you anticipate your opponent will use a projectile attack you can jump over it and jump kick and sweep combo your opponent or use a jumping punch and shoryuken combo.
The super combos are a great way of turning the tide in a battle and to win from a seemingly unwinnable position.
All the characters from the original Street Fighter Alpha are back,and new characters such as Akuma,Gen,Rolento,Zangief,Dhalsim,Sakura are added(you will recognise some of them from SFII or Final Fight games.Shin Akuma and Evil Ryu are secret selectable characters.Shin Akuma can do 2 air fireballs and he's very powerful and is also a secret boss.
The new characters make the story deeper.
Akuma learned a form of martials arts designed soley for killing and he wants to test his abilities against only the strongest opponents such as Ryu.Akuma has a demonic appearance because the evil inside him has changed his appearance.
Gen makes his first appearance since the original Street Fighter game.He may be old but his fighting techniques can punish anyone lets their guard down.
Rolento is the final boss for another Capcom game named Final Fight and he is the former leader of the Mad Gear gang who used to terrorize an entire city.He isn't ashamed to use grenades and a spear that uses to impale opponents with.Although he was wheelchair bound in final fight,in Street Fighter Alpha 2 he can jump around all over the place and do somersaults.
Sakura sees Ryu as an idol and wants to fight him when she isn't busy with school.She even tries to copy Ryu's techniques while inventing moves of her own.
Evil Ryu is Ryu's evil side that was awoken when he fought and defeated Akuma's weaker form.Ryu knows if he fights Shin Akuma,he will need to awaken his evil form again to defeat Shin Akuma and the loser of that encounter will surely die.
The environments look more interesting and colorful.You'll fight Rolento on a scrolling construction lift and you'll see colorful sign board ads of sexy women in bikinis.
Adon fights in front of a river in Thailand and you'll see the boat people and Thai countryside.You also hear entertaining rock music playing during the battle.
You'll face Ryu in the snow for a nice Japanese winter effect.
Charlie is at a military base with Jet Fighters and a lot of lights.
Dhalsim takes you back to India
Sagat's stage has a nicer looking Budhha statue.
The storylines in SFA2 feel more deeper,and every character has a secret rival and main rival(boss)
SPOILERS BELOW
Bision's final boss is Ryu because he wants to capture Ryu and learn about Ryu's powers.Zangief's final boss is Ken beacause Ken insulted Zangiefs beloved USSR.Dan wants to get revenge on Sagat for killing his father(you'll see Sagat break Dan's fathers neck before Dan fights Sagat)and it's explained Da'ns father was the one who took Sagat's eye.Guy still feels hatred towards Rolento for the murders,assaults,rapes,robbery,extortion,kidnappings the Mad Gear Gang did.Sakura just wants to fight her idol,Ryu.
END OF SPOILERS
The music is great too,I love the electric guitar music when you fight Adon.
If you love Street Fighter you need to play this game,and the Sega Saturn version of it is the best console version of it(even better than the Street Fighter Alpha Anthology version).