AGP Pro cards are mainly professional videocards that need more power.
They
get that extra power from the AGP Pro slot´s extra connectors.
Speed has nothing to do with this.

I am curious what is then the difference between nonpro cards and pro cards.
The speed is the same, so why do they need extra power? Do they just turn it
into extra heat or do those pro cards have other advantages.
This may sound sarcastic but it is not, I am really curious for I don't know
what the difference is between the cards that are used for gaming and
professional cards.

Greetings,
René