Creighton float pool and choices per diem programs

Can anyone tell me the difference of choices per diem vs float pool per diem at Creighton University Medical Center. Choices per diem shows the tiers I and II with the pay scale to those areas, also states that no benefits are accumulated. The float pool per dium does not state those things, I have been offered a job in the per diem float pool but the offer they gave me is quite less than the lowest of the tiers of Choices per diem. I am excited to start working at Creighton but will lose money in traveling expenses without the extra pay.