Reharmonization and substitutions

[idssdi]

I need some help on these two because I think I got myself a little confused. Reharmonization is basically changing the chords underneath a Melody right? Isn’t that usually just a substitution? And does that make the concept of substitution kind of like a subsection in a chapter on reharmonization?
Just to make sure I kinda get it. Thanks for your help!

 

[Guest]

I believe the differences are;
Reharmonisation is changing the position of the chord with different inversions, so you might consider the movement between chords to create some linear sense. So it kind of is substituting.
However, substitutions is replacing one chord for another following different rules (depending on how you want to change the individual chord)