A cheap floodlight will embarrass you within a year, usually right when you need it most, flickering or dead in a downpour with someone standing at your back door. Good outdoor lighting is not a place to cut corners, because it is the one fixture that has to perform in weather you would not stand in yourself.
The difference shows up where you cannot always see it. A well made floodlight has a sealed housing with a real gasket, not a thin bead of glue that gives up after one hard winter, and the rating to back it up rather than a sticker that implies one. The mounting bracket should feel solid enough that you are not worried about it sagging under its own weight after a year of sun and rain, and the finish, usually a powder coated or anodized metal rather than painted plastic, should resist chalking and rust where it meets the wall. Cheaper units tend to use thinner lenses that yellow and crack, and connections that corrode at the screw terminals, which is where most outdoor electrical failures actually start. None of this is visible in a listing photo, which is exactly why so many people end up disappointed.
For where it fits, think about the parts of a house that get used in the dark without much thought, a driveway, a side path, a deck where you grill through fall, a back door you come in through with groceries in both arms. Floodlights suit homes with some land around them or at least a yard that gets used after sunset, more than a tight city balcony where a wall light does the job better. Older houses with uneven siding need a bracket that adjusts enough to sit flush, and anyone in a place with real winters should care more about the seal than the style. When it arrives or you are standing in a shop, check the bulb or built in LED is rated for the fixture, check the glass or lens is not already scratched, and look at the cable entry point, that is the part that fails first if it is not finished properly.
Where it is the wrong choice is anywhere you want ambiance rather than coverage. A floodlight will wash out a patio dinner or a quiet porch sit, it is a security and visibility fixture, not a mood one, and if softness is what you are after you want something warmer and dimmer entirely. It is also overkill for a small courtyard that a single well placed wall light could cover.