Read as "types of round robin bets", the answer starts with one ticket. A parlay, called an accumulator in many places, joins several picks into one bet. Every leg has to win for the ticket to pay, and the odds of the legs multiply, so a small stake can return a large sum. What makes the format attractive is the same thing that makes it hard: each added leg lowers the chance that the whole bet comes in.
A push, where a spread or a total lands exactly on the line, does not win a parlay and does not lose it. Most books treat a pushed leg like a void one: it leaves the ticket, and the parlay pays on the legs that remain. To define a same game parlay simply: several picks from one match on one ticket. Because those picks are linked, the book prices the combination itself, and its margin on a same game ticket is wider as a rule.
Several types of combination bets soften the all or nothing rule. A round robin splits a list of picks into every smaller parlay, doubles or trebles, so one loss does not end every ticket; round robin bets cost one stake per combination. An anti accumulator bet reverses the logic and pays when at least one leg loses. Systems with names like trixie or yankee are round robin bets with fixed sizes and a fixed count of lines.
Asked about this
Why does adding legs to a parlay raise the risk?
Each leg multiplies the odds, but also the book's margin and the chance of failure, so three picks landing half the time win together only one time in eight.
What is an anti accumulator bet?
A bet that reverses the usual logic and pays out when at least one of the selected legs loses.
How much should go on an accumulator?
A small stake treated as entertainment money priced in advance, since multiplied margins make accumulators a poor way to earn.
How does a round robin bet work?
A round robin splits a list of picks into every smaller parlay, such as doubles or trebles, costing one stake per combination so a single loss does not sink everything.
What happens when one parlay leg loses?
The whole ticket is lost at once, whatever the results of the other selections turn out to be.