I’ve always wondered this, and the internet at large also doesn’t seem to know the answer judging on a few google searches. I always assumed the Chili Mac was Chili on Macaroni while the Chili 3-Way is the “Skyline Chili” style of spaghetti with chili on top, but I just had a Chili Mac after only having their Chili 3-Way and it’s still served with regular spaghetti and noticed no difference between the two.
According to their general menu
CHILI MAC SUPREME
Our original Chili Mac plus diced, fresh onions and
shredded cheddar ’n jack cheese.
CHILI MAC
Spaghetti topped with chili beef and our special
chili sauce.
CHILI 5-WAY
Spaghetti topped with chili, extra chili beef, our special chili
sauce, diced onions, and shredded cheddar ’n jack cheese.
CHILI 3-WAY
Spaghetti topped with chili, extra chili beef, and our special
chili sauce.
According to this the only difference between a Chili Mac and a Chili 3-Way is the Chili has “Chili” but they both still have Chili Beef and Chili Sauce which seems kind of the same thing.