Someone asked me that question last week. We all know the answer: none. It's just a damn title. Title doesn't matter. It never does. Batman once said: it's not who you are underneath, it's what you do that defines you.
In my current organization, that focuses on consulting services, there is a distinction between Solutions Architect and Technical Leader role in career path for technical person. (Himawan, but you said there is no such thing as career path? Well, let's save the debate for some other time).
As seen in below figure, Network Consulting Engineers (NCE) make progress from level I to level IV, and this is the point where he/she can make decision: either to stick as NCE then becomes Technical Leader someday, or to move to become Solutions Architect. He/she can actually move to any other position across the organization like pre-sales consultant or project manager or business development manager or even accountant! But let's keep the discussion between the path of Technical Leader and Solutions Architect.
So what's the difference between the two then?
Both must have excellent soft skills: communicate effectively, above average presentation skills, team player and so on. Both must have superb technical skills. Both must face customer in various projects from time to time so it is expected to have customer oriented mindset.
Perhaps the difference is in the focus: a Technical Leader should be a Subject Matter Expert in one or more technologies. A Solutions Architect, as the name implies, should be focusing on end-to-end solutions architecture. Technical Leader should put more focus on deep down technical stuff, while Solutions Architect even must still required to be a techie but the focus is on providing the complete solutions. Technical Leader produces white paper. Solutions Architect considers business architecture.
In reality it's really hard to find the distinction when both roles are in the field. I have worked with so many Technical Leaders and Solutions Architects and even Network Consulting Engineers, and they all pretty much do similar things. They all have the soft skills, technical skills, and customer oriented mindset. Throw away more responsibilities to these individuals: lead the project execution, manage team resources, build project schedule. Ask the individual to perform pre-sales: define the scope of work and calculate mandays. Let him or her integrate the whole solutions with another vendor. And the result is the Superman in networking.
But even Superman gets weak by kryptonite. Or fall to his colleague reporter. Is there anyone stronger that Superman?
Meet the Distinguished Engineers. They are way above both. They are the gatekeeper of computer networking industry. They work in leading edge technology from time to time. They are usually part of the expert community who write Internet standard. They were the first in my organization who talked about IPv6 or SDN. They involve first-hand then spread the knowledge to others. When people start talking about it they have already moved on to the next topic like Internet of Everything. They shape the future of the technology. They are the kungfu masters. They are the Immortals.
How about myself? Even my official title is Solutions Architect, I usually do all what I explained above: lead project, provide technical solution and design, talk business, do pre-sales, manage resource and so on. But I'm not the Superman. Most of the time somebody make a mess and I get called to clean it up. I won't discuss it in more detail here but let's just say I'm needed the most where it's required to connect the broken pieces. To wipe the floor. So I prefer to call myself the Janitor.
Superman, Immortal, Janitor. Which one do you want to be?