Attack speed is just that. Attack speed.
What really is different is the affixs.
Attack speed % and Attack per second.
Attack speed % increases by percent.
For example: Imagine you have a sword with 1 attack speed..
Now add 10% increased attack speed, and now you have 1.1 attack speed.
100% will increase that to 2 attack speed.
Now adding attacks per second is very similar but just shows it as a decimal.
For example: Imagine you have a sword with 1 attack speed..
Now add 0.1 increased attack speed, and now you have 1.1 attack speed.
1.0 will increase that to 2 attack speed.
What really is different is the affixs.
Attack speed % and Attack per second.
Attack speed % increases by percent.
For example: Imagine you have a sword with 1 attack speed..
Now add 10% increased attack speed, and now you have 1.1 attack speed.
100% will increase that to 2 attack speed.
Now adding attacks per second is very similar but just shows it as a decimal.
For example: Imagine you have a sword with 1 attack speed..
Now add 0.1 increased attack speed, and now you have 1.1 attack speed.
1.0 will increase that to 2 attack speed.