The movies are so different, it's like comparing apples to oranges.
In 'Jarhead', Jake played a young man who undergoes a transition from life to numbness due to the futility and violence of war, you can see Swoff cracking under the burden at the end.
In 'BBM' Jake played a young man who played two roles in life, leading to grief and tragedy.
No question, 'BBM' is the more challenging of the two roles and Jake's best performance to date.