Hello Trevor, thanks for asking this question. Both flags and pennants are popular trading patterns. What they have in common is the fact that both are classified as continuation patterns. In layman terms, their job is to help the current trend extend higher/lower. Moreover, both can have bullish and bearish versions.
The biggest difference between these two is that the consolidation phase takes the form of a triangle in the case of a pennant. On the other hand, the parallel channel is formed in the flag pattern to help the price action consolidate.
The flagpole is the same, hence you should only pay attention to the format of the consolidation phase. Overall, both are very powerful and strong continuation patterns that are activated once the breakout is confirmed.