diff between nearline and coldline

Nearline is for data access that is once per month, whereas Coldline is for once a year.  Both nearline and coldline keeps the storage costs much lower than the standard cloud storage, but they have a retrieval cost. For instance, if you store the data in coldline but need regular access, while storage cost is lower, then retrieval cost could be much higher than if you keep your data at normal or nearline.