Disclaimer: I applied and was accepted to both Northeastern and BU (which I eventually chose).
In terms of raw rankings, Northeastern has a more established engineering department. That, plus the coops practically guarantees a job for you by the time you graduate. That being said, BU has some incredible engineering resources that Northeastern (or even MIT!) doesn't have, such as a open-access machine and prototyping shop (Boston University College of Engineering Singh Imagineering Laboratory
) and free tutoring for most (if not all) engineering classes. As for scholarships, I think Northeastern has a slight advantage for merit scholarships, whereas BU is more likely to give financial aid.
I'm not fully sure if I've made myself clear, so feel free to ask if you have questions, and good luck with the apps!