In general, according to Jordan Tourism Board website (http://international.visitjordan.com/page/4/VisasToJordan.aspx), there are three types of visa used to enter Jordan. (Note: subject to change)
First, is the visa which you will need to obtain from the closest Jordanian Embassy before you arrive.
This is applicable to the following nationalities: Afghanistan, Albania, Angola, Bangladesh, Belize, Benin, Botswana, Republic of the Congo (Brazzaville), Burkina Faso, Burundi, Cambodia, Cameroon, Central African Republic, Chad, Colombia, Comoros, Congo (Kinshasa), Côte d’Ivoire, Cuba, Djibouti, Egypt, Equatorial Guinea, Eritrea, Ethiopia, Gabon, Gambia, Ghana, Guinea, Guinea-Bissau, Iran, Iraq, Laos, Liberia, North Macedonia, Madagascar, Mali, Mauritania, Moldova, Mongolia, Mozambique, Myanmar, Namibia, Nepal, Niger, Nigeria, Pakistan, Papua New Guinea, Philippines, Senegal, Sierra Leone, Somalia, South Sudan, Sri Lanka, Tanzania, Togo, Uganda, Vietnam, Yemen, Zambia.
Second, is the visa exemption, which means you will not need to go to Jordanian embassy or pay anything upon arrival.
This is applicable to the following nationalities: Bahrain, Kuwait, Oman, Saudi Arabia, UAE, Vatican.
Third, is the visa on arrival, which you need to pay upon arrival at the price of 40 JOD (Note: subject to change).
This is applicable to nationalities not mentioned in the first two types of visa above.