In a sense, depositing money in a bank is a sort of loan to the bank. They then loan your money out to others, and give you a cut of the interest. It isn't really "held in an account," rather there is a register which says how much money you loaned to them.
True, but it's very different than an investment. They're holding your money in trust. And significantly, no purchase has taken place. You haven't traded your money for equity. You haven't traded your money for anything at all. Thus, it is still your money legally. That's not at all true when you buy equity in a company. When you do that, the company really does own the money you give them, and they're free to do what they want with it. In exchange for transferring ownership of your money, you get equity.
