Difference between TIMER0_A0_VECTOR and TIMER0_A1_VECTOR

Teh TIMER0_A0_VECTOR is exclusively used for the CCR0 capture/compare event. Since CCR0 has the capability to reset the timer in up or up/down mode and therefore define the timer cycle, it has been given an own, higher priority interrupt. Also, the CCIFG bit in CCTL0 is automatically reset when entering this ISR, as tehre is only one possible reason for this interrupt.
On A1_VECTOR, you'll have to check what was causing the interrupt and manually clear the IFG bits (or clear them by reading the TAIV register)

On the bottom line, the separate A0_VECTOR allows extremely short reaction times to the CCR0 event, which is necessary for controlling a PWM duty-cycle change or other situations.

Thank you very much, great explanation!