When adding ties and slurs are
 

When adding ties and slurs are they strictly cosmetic?

Howdy George, Slurs are 
 

Howdy George,

Slurs are "cosmetic" in that they convey to the musician how the note(s) is to be played, but don't affect the performance in Composer. Ties are "functional" as they both convey the performance to the musician, and they affect the performance in Composer.

ttfn,
Sherry