Systems thinking vs algorithm thinking

I was chatting with another programmer about our different styles.  He's an incredible algorithm solver.  He's done compression and encryption algorithms in school, and codecs and video processing and GUI animation effects since (he's 23).  I tried to explain the kind of problem that I'm attracted to, which none of those are, and used the word "systems problems".

"But isn't everything a system?".   Only in the most trivial sense.

What I was trying to distinguish by talking about systems problems and systems thinking in programming is modeling independent and interconnected agents.  I'm not the only one with this kind of definition.  In an interesting publication on managing social change, I saw the definition "Systems characterised by interconnected and interdependent elements and dimensions are a key starting point for understanding complexity science."  Very close.  Is there a better phrase for system-style solutions as opposed to algorithm-style solutions?

Another way I explain this approach when I'm being self-mockingly post-modern is to say "I'm interested in the liminal spaces in computer architecture", which is an arty/jargony way of saying I'm interested in the interfaces between agents: APIs and protocols, typically.   I also hear the words of a British-accented UWaterloo professor from 20 years ago, saying "Modularization!" and "Information hiding!" over and over.  (Systems thinking supports object-oriented design.)

I've worked with a ton of people who have the same mental models because I worked a lot in the IETF for ten years.  It's a necessary part of communications security in particular, because in addition to thinking of each client and each server as ideal agents, one must always think of bad actors and flawed agents.

Coming back to startups, I'm always surprised in a way when I talk to a programmer who doesn't design and implement protocols and APIs because they think so differently.  It's more justifiably shocking when I meet people who know about and implement REST and aren't used to systems thinking!