When you're caught, you have a new option to offer an automatic percentage like a quarter or third of the value you've stolen, the guard may say "You're not gonna bribe me, criminal scum" and you are given a chance to save your scalp trying with a juicier amount closer to the total.
This may succeed or not based on Speechcraft and naturally his standing towards you, but if it doesn't you're forced to pay a now bigger bounty, go to jail or resist arrest.
Because thieves are thieves, guards are guards and you know the deal among them.