Decreasing diameter of the prop (actually it's the length of the prop, since it's not circular in shape
) and increasing pitch and rpm can net similar thrust, up to a point. It's really not that simple, however.
Generally, a larger diameter, slower turning prop of a relatively low pitch is more efficient aerodynamically and will produce more usable thrust than a smaller, high pitched one turning at high rpm. The larger prop disc moves a larger volume of air per revolution, but the lower pitch results in a lower inflight maximum airspeed (aka pitch speed). Smallish, high pitch props are more intended for fast, sleek airframes, and in extreme circumstances, the blades can actually be stalled when rotating, at low or zero airspeeds of the plane. The pitch on them is such that the AOA of the blades is too steep to produce much lift (thrust) until the plane is moving forward.
It's really a matter of experimentation to find the most efficient prop for a given application, WRT thrust, pitch speed, and amp draw. All three parameters play a role, so it's a balancing act. In general, you should choose large, shallow pitch props for slow-flying planes (like trainers and WWI planes), and small, higher pitch props for fast ones (like WWI warbirds and such).
Rick