Commerce refers to trade or business, specifically the buying and selling of goods and services. Ecommerce refers to buying and selling online through electronic data transfer and payment.
The document describes common ecommerce business models: Business to Consumer (B2C) where businesses sell to individuals, Consumer to Business (C2B) where individuals sell to businesses, Business to Business (B2B) where businesses sell to other businesses, and Consumer to Consumer (C2C) where individuals sell to each other. It also discusses Business to Administration (B2A) and Consumer to Administration (C2A) models involving government. Examples are provided for each model type.