I don’t agree, it’s consecutive line output vs. screen-based rendering and repositioning. Regardless, ed was developed for and used on actual teletypes. It’s entire interface is geared towards that usage.
I think ed also served the function of sed and patch. Ie you could record a bunch of edits into a file and it could read the script and perform all the edits to some input file. So it was more useful than an interactive line based editor sounds.
This is the same distinction as between running commands with bash -c (or just by executing a regular Bash script) and running them manually in an interactive Bash session. It’s pretty much an inherent feature of command-line interfaces that you can script them.
It's different. Grep was a function of ed ('g/re/p') that was later extracted into its own program to search files that could not fit in memory. Sed then came along and implemented the 's/re/substitution/' functionality from ed for the streaming use case.
But as to that, it's slightly different than merely being able to play back a recording of commands. It IS that, but that can be applied in a way that acts more like the examples I said like sed or patch, or expect, where the script can apply some funcion to different inputs, not just playing back a recording. I'm not denying the implimentation, how the job gets done, is technically still just a recording of commands.
