I don't think there is a clear definition. My company
isn't small (5000+ employees worldwide) but we have
Solution and Technical Architects.

In our company the Solution Architects deal with the
broad scope of a solution, i.e. "right, we'll use a web
service here, biztalk there and run it all off SQL
Server.". They have heavy involvement with the
user/customer and are the 'visonarys'. They understand
technology since they have to know something will work
but are perhaps more convinced by the sales pitch than
say, a Technical Architect would be.

Solution Architects sometimes cross-over with business
process engineers since they have heavy involvement the
user and have to work closely with them in defining the
process that the solution must fulfil.

Me, I'm a Technical Architect. I have to understand the
technology in detail - I'm not so convinced by the sales
pitch :-)

I'd get a broad sweep solution probably half way through
conception and work with a Solution Architect ensuring
there are no 'quirks' that will catch us out. I'd take
the overall solution and design it in more detail (e.g.
via UML and maybe a few prototypes) and work with the
development team in producing it. Depending on the
experience of the team significant components may be
handed over to lead developers to design, though I will
confirm it fits into the overall solution.

I think that System Architect is similar to what has
already been mentioned and that Application Architect
could fit into the Solution or Technical roles... but my
guess would be that its another name for a Technical
Architect.

Graham