As we can see from this exercise the f-stop relates to the depth of focus i.e. the area of in focus. The smaller f-stop isolates the key object and places it against a blur of a background, the area of focus is small. At the larger f-stop a far greater section of the image is in focus. Use of f-stops can lift an object from its background, setting it outside its surroundings, or embrace the entirety of the frame pulling in all the details. Again a tool. To be used as appropriate and with degrees. The image at f4 also seems to contain an almost vignetting effect. Can be sentimental and over used, harsh and unreal. All these effects can be clumsy.