[I7] run paragraph on vs. no line break

Does anyone know the difference, assuming there is one, between the “[run paragraph on]” and “[no line break]” text substitutions?

There is a difference.

Now you have to read the I6 source code in Printing.i6t. This won’t make you any happier, but if I try to explain it I’ll get it at least as wrong as you will.

Ha, good enough.