Visa-free travel allows passport holders to enter a country without having to obtain a visa before or upon arrival. One would not have to pay any fees for a visa or obtain a visa overall to enter a country.
Visa on arrival is a visa that is granted at the port of entry for travellers. One will have to apply for a visa only after landing in the country. The entire process of visa issuance is done at specific ports of entry. This is a quick procedure where documentation and fees are also collected.