Apply for both and make your decision based on your fit with the hiring manager, their interpretation of leadership, field-support, and their input on the SBU's senior leadership team. Ask tough questions pertaining to your short and medium term career goals, anticipated professional development, career mapping and realistic expectations. If its vague, red flag. If its clear and well laid out, then ask more questions. You will quickly learn which hiring manager has your best interest in mind. Reach out to current as well as ex-reps/managers from both SBU's via social media like LinkedIn. Ask relevant questions.