What is the difference between air transportation and express delivery?

International express delivery refers to the delivery of letters, business documents and goods between countries (or regions). International air transport refers to an international logistics mode in which goods are mainly transported by air between two or more countries (or regions).
The main carriers of international air transport are major airlines, such as Air China, JAL, SIA, Shenzhen Airlines, Thai Airlines, Malaysia Airlines, Northwest Airlines, etc. Freight companies transport the goods to be checked by customers to the designated destination (i.e. the airport of the receiving city) through these large international airlines.
The main carriers of international express are major express companies, such as China Post EMS, DHL, TNT, UPS united parcel, FedEx and other major international express companies. The packages we want to mail are mainly transported to the destination through these international express companies.
International express: "door-to-door" - pick-up, customs clearance and delivery. International air transport: the traditional international air transport is mainly delivered by the shipper to the airport, and the guests at the port of destination or their agents pick it up at the airport warehouse - no customs clearance or delivery; There are also a few who do "door-to-door".
International express: including domestic and destination customs clearance agency services, including delivery, but excluding destination customs duties. International air transport: it does not include customs clearance of the destination country. Guests need to pick up the goods and clear customs at the airport by themselves, and it does not include customs duties of the destination country.