What is the definition and difference between conjunction-class and opposition-class Mars missions according to the source?

In the source, a conjunction-class Mars mission is one that uses low-energy transfers to Mars and back, with a long stay at Mars of roughly 500 days, so the total mission lasts about 1,000 days.^[1] An opposition-class mission uses one low-energy transfer and one high-energy transfer, with a short stay at Mars, typically less than 30 days, so the total mission lasts about 600 days.^[1]

The main difference is that conjunction-class missions minimize propellant by accepting a much longer mission and surface stay, while opposition-class missions shorten the stay but require much more propellant because one leg of the trip is high-energy.^[1]