No matter how large or small the system, there is a constant hierarchy that is applied to everyone in the design chain, as shown below:
System Engineer
Designer
Implementation Designer
If you are the designer, the System Engineer is one level up from you, and the Implementer is the next level down. Sort of a Grandfather/Father/Son relationship. Every designer (Father) has a grandfather (System) and a son (Implementation).
A system engineer provides requirements to a designer, and the designer provides feedback to the system engineer. This relationship is the same as the designer to the implementer. Typically, the "system" engineer will communicate and integrate the effort of several designers, and a designer to several implementers. Your system engineer is a designer at the next level up, and so on.
Consider an aircraft design. There is a chief System engineer of the aircraft. Under him, System wise, is the pilot interface designer, and below him is the display designer. Each of these is a system engineer to the next element in line, and an implementer as far as the next person up is concerned. The manufacturing engineer may be the last design stop. That's design? Sure. The tooling and machine setups, as well as the procedural controls, show many of the traditional elements of design.
So everyone looks up to their system engineer, and down to their implementer(s). Following this method, very large undertakings can be broken out - like skyscrapers, transcontinental railroads, or moon shots. But it also applies to something as small as a microwave oven. The oven has mechanical system, electrical system, an RF system, and a user interface that includes some firmware, etc. It is a "system of systems", you can buy for $49.
Here is the designers definition of implementation (the next step down):
To Implement is to execute a specific series of steps which has a single, repeatable result.
To a designer, design is the process of selecting and documenting the proper implementations that meet a set of requirements, provided by the System engineer. Who is the designer at the next level higher, because he received his higher level requirements from his system engineer one design level up.
For example, a printed wiring board is designed by a PWB designer, and implemented by a PWB house. The PWB designer requirements are captured in the schematic, parts list, and assembly drawings. Software is designed by a software engineer, and implemented by a coder. The coder then passes it to a compiler, which is an implementer for the coder.
The PWB designer is the the electrical engineers implementer. The next level down, the Printed Wiring Board house, the PWB designer appears as the System Engineer. The designer at the PWB house takes the data output provided by the CAD designer and integrates it with their process to make it compatible and optimize the yield, using the same design methodology as any engineer. He then passes his design to his implementer, who etches and drills.
Business Managers want to treat all tasks as implementations. In their world, every task has a known duration, every task has a fixed cost. They know they need designs, but try to keep them to a minimum. Design is black magic, as far as they are concerned, and they either steer clear of it, or assume that anyone can do anything (magic, remember?).
Engineers start by treating all tasks as designs - they don't know, they haven't figured it out yet, everything is open. And to a designer, implementation is boring, and doesn't advance the state of the art. As the overall design progresses, the good designers will design the sections that require something new or unique, and implement the remainder.
Project Managers have several methods of getting a handle on technical task costs and durations, to bring these together.
Since implementation is considered to be a fixed set of steps, it usually has a defined time and effort, from the designers point of view. Design, on the other hand, has breakthroughs, dead ends, and improvements until you reach diminishing returns. Implementing on a deadline is usually concentration and elbow grease, and you are not finished until all the checks pass. Designing on a deadline means going with the best solution you have come up with when it is time to go. Some designers don't understand this, some do. So an important consideration for any engineering task is how much of it is design, and how much implementation.
Implementation problems are usually operator errors or uncontrolled processes, that are coped with using classical quality control methods. Design errors can be caused by these, but also are caused by misunderstanding of requirements, unforeseen complications, or errors in judgement (I thought it would work).
Summary
So like a Russian novel, what you are called depends on who you are talking to. You talk up to your system people, and down to your implementation people.
Oh, and sometimes, the lowest level designs may involve the biggest technical challenges, thus have the heaviest hitters, academically speaking. Examples are antenna design, or three dimensional packaging for a folding assembly. Moving up a level in the system design hierarchy does not imply more experience or status, but rather a broader skill set than the designers below. The system design may be quite elementary, and the real difficult problems to solve in the implementation. Look at an electric car battery system for an example of this.