Corporate accounts would be expected to be larger..also they are generally calcularted on a 360 day basis as opposed to 365 day basis for personal accounts.
There's generally room for negotiations with a corporate account in regard to rate as well - so generally 4.71% would a guide.
Not sure that I understand the point about the account being larger. I would have thought 10 personal accounts at 100K has the same value to a bank as 1 corporate account and 1M?
Its a lot to do with the propensity/risk for repayment
The reason for this is that the likelihood of losing 1 corporate account for €1m is higher than 10 accounts for €100k each.