Typically an 8.5 x 11.0 card stock that has bulleted points and topics of interest to a buyer. Designed to be left behind as a general outline of services and products offered. It can be printed on the face and/or face and back. It can be 3 hole punched and inserted into a binder, usually at the beginning as a quick reference to products and services.
Your site map if constructed properly may look exactly like your line card. The two are synonymous of each other. If your site map is becoming too large, consider breaking it down into multiple site maps, each one related to a specific category and linked to from the category pages. Believe it or not, I've had some clients tell me that they wanted their line cards to mimic their site maps! I'm in the printing industry.