As is clearly visible in the provided carousel, the lens of a camera directly affects the zoom of it; larger amounts mean more zoom, and smaller amounts mean less. While 200mm is directly in the model's face, 15mm covers almost the entirety of the room, and makes the model almost look like a speck.
Clipping masks, unlike in softwares such as photoshop, essentially dictates how far the camera can see, abruptly cutting anything past the "far clip," which is the farthest length the camera can see to, off with a black void. We didn't experiment much with this setting, so extremes haven't been pushed, but the general idea is visible.
The difference between target and free cameras is, I would argue, a major one. Target cameras have a target (no way, I know) that the camera itself latches onto like a magazine reporter latches their camera onto a celebrity doing literally anything; that is to say, it is quite literally impossible for the target camera body to look away from its target. Free cameras are much more like the a movie camera in a scene involving tracking a moving object; the free camera can be moved any which way in any direction, and the direction it looks to stays the same, unless you change its rotation.
The physical camera is like the target camera and free camera all-in-one! Not only that, but there's more camera types (which I won't get into here)! The physical camera has everything you would ever need. I see no reason not to use this other than to specifically be able to sort cameras through the objects tab alone, which is kinda stupid when you realize you can name objects. Changing a physical camera's settings work like they would on any other camera, there's lenses, clips, etc. Some other options used here that either weren't on the other cameras or just weren't mentioned during their sections includes: white balance, which does something to how cold or warm an image is, I think; exposure gain, which directly affects image brightness; zoom, and focus length, which I have no idea what that does, but it was mentioned in my overly detailed file name so I'm mentioning it here.
To summarize what I just wrote (AKA a TLDR): lens size is essentially zoom, clipping masks affect how far or short-sighted the camera is, target cameras snap to their target, free cameras don't have a target to snap to and thus don't snap to anything (now breath), and physical cameras not only are both free and target cameras at the same time, but are simultaneously better. Well, I suppose I've shown my hand too soon; I must admit: Physical cameras are the better of the three cameras. I see no reason to use the other two, as the physical camera both encompasses and eclipses both, which is why it is my favourite. I don't know how much that means because it's just a digital camera, but I thought it worth mentioning.
Top-Down Camera Placement