The C&R license allows you to buy guns that are defined as "curios and relics" in interstate commerce. It allows you to buy certain guns on the ATF C&R list or guns that are more than 50 years old direct from the importer or distributor and receive them through UPS or Fedex at your home. The license must be used for collecting purposes, not to run a business or make good deals for friends. Your collection and records are subject to audit by the ATF. The audit can be at the ATF local office.
The "01 FFL" allows you to run a business that sells firearms. You have to have business hours, a place of business, and actually engage in the business of selling firearms. The ATF can come to the place of business and audit records and firearm inventory. You also have to have to be in compliance with all state and local laws regarding running a business.
Hope that helps.