STV
STV usually makes voters rank each candidate as an individual.
Party List
Voters mark their ballot for 1 party. These ballots look like the ones used for single-winner plurality rule which lets a voter mark his ballot for 1 person.
Quotas
When no party has a full quota left and there is still an unfilled seat, which party gets it? It might simply go to the party with the largest number of "leftover" voters. Or it might go to the (small) party whose leftover votes, divided by its number of reps, make each of them represent much more than one quota of supporters. The quota rules sometimes used are described two sections back.
Divisors
The d'Hondt and Sainte Lague rules are the most common. They use a series of divisors. Sainte Lague favors medium sized parties and is used in some Scandinavian nations. Continental nations are more likely to use the d'Hondt divisors. These and other divisor rules are described in Taagepera and Shugart's fine book.
