@PengsPhils – by “Application Science” I’m referring to the design and creation of programs for end users (as opposed to operating systems, compilers, low-level library stuff, etc.). Software engineering techniques would apply to both of them. AS would focus on creating programs that are usable by real people. There would tons of human-computer interface study, data gathering and presentation study, etc to go along with programming. AS people would use the tools/APIs/libraries created by the CS people.
Two things prompted my AS/CS split thinking. A few days ago, DW was completely frustrated with one program she was using and lashed out at me with, “you programmers think you know everything about computers … but you don’t”. The second thing was when I tried to develop a decent iOS and Android app. The APIs were inconsistent, buggy, and had undocumented limitations. The most appalling one to me was the text boxes being limited to the maximum size of a texture on the device’s GPU. Just inexcusable laziness on the part of the OS developers. These two problems require different levels of thinking about software design. It took me several years to transition between the two.