Different between printable coupons & coupon codes?

It might sound weird and it's pretty obvious to tell the different between the two, so why the title? Well, I just recently stumble across coupons site while searching for some printable coupons that I can use in-store, but end up finding lots of coupon codes of online use instead. I have been reading the comments left by some poster asking how can they print the coupons with a set of code. Of course you can't those are code for online use, there's no way you can print them out and use it in-store. It surprises me some time how ignorant people's can be. Or maybe they are just not techie enough to understand the difference between the two unlike me who are writing this useless post. Anyway it's a weird rant and I thought since I haven't post anything in such a long time, why not?