What is the difference between "building" and "making"?

"Build" has the connotation of taking deliberate and possibly complex steps. "Make" is using for any kind of creation.

You build a car, but make a mess.

Until recently, "building" would only be used of a physical construction where parts fit together, usually with some structural complexity or permanence, though now the meaning has also been transferred to non-physical domains (eg software system, company, relationship) but still with the connotation of (relative) permanence, and of pieces fitted together in an ordered way.

It would be odd to use it of a dish, because the result is not intended to be in any way permanent. I could imagine a cookery writer talking about a chef "building" a cake or a pie, but that would be a deliberately non-standard use to make a point about the complexity or solidity of the result.

Your example of a bank is interesting: "I am building a bank" would unequivocally say that you are creating the building (and not that you necessarily have any connection with the bank itself: you might just be a builder), whereas "I am making a bank", though unusual, would imply that you are creating the bank as a business and not as a building. (In line with the metaphorical extension I have mentioned above, I could just about imagine somebody saying "I am building a bank" with the second meaning, putting an emphasis on all the different structures and processes they need to put together to create a banking business; but they would be liable to be misunderstood if they said this).