identify different groups of depositers being targeted by thr bank?

Answer 1

Are you asking how, why, or if it is legal?

How is easy - for FDIC insurance purposes, all institutions must keep track of a depositors' accounts and the amount of funds therein.

Why - because targeted marketing is more effective than blanket approaches.

If it is legal - unless the bank is engaging in redlining (selecting a group on criteria other than deposits or something appropriate), there's no restriction.