The chap is smaller, with a thinner blade, and a back lock (only sage 4 has back lock). It should fit more squarely into a gent's folder whereas the sage is very much into the EDC/all-purpose knife IMO. Sage has a 3" blade and chap has around a 2.75" blade.
I wouldn't underestimate the finger choils. Spyderco does it better than anybody, making a little knife blade fit bigger hands combined with ergonomics. Their downside is they have some ugly looking knives but some of the most functional.
I think a chap with a sage would be a great EDC combo or just a nice looking matching pair. Chap for really nice dress or when you want a thin blade, sage for anything under battoning.