Cash GameCash games and tournaments are different poker variations. The participants play for and make wagers in cash. The participants buy into a table and can bring in new money to the table at any time, so long as they do not step over the maximum buy-in for the table.
No-limit and Pot-limit games are often called cash games since the players bet as much as they want, as opposed to fixed limit variants where the bet sizes are constrained to discrete steps. Fixed-limit is not viewed as "real" poker in this sense.