Prior to the invention of poker tournaments, poker games were played with real money where players bet actual currency (or chips which represented currency). Games which feature wagering actual money on individual hands are still very common and are referred to as "cash games" or "ring games".
The no-limit and fixed-limit cash game versions of hold 'em are strategically very different. Doyle Brunson claims that "the games are so different that there are not many players who rank with the best in both types of hold 'em. Many no-limit players have difficulty gearing down for limit, while limit players often lack the courage and 'feel' necessary to excel at no-limit." Because the size of bets is restricted in limit games, the ability to bluff is somewhat curtailed. Since one is not (usually) risking all of one's chips in limit poker, players are sometimes advised to take more chances.
Lower stakes games also exhibit different properties than higher stakes games. Small stakes games often involve more players in each hand and can vary from extremely passive (little raising and betting) to extremely aggressive (many raises). The difference of small stakes games have resulted in several books dedicated to only those games.
From Wikipedia's
Texas Hold'em Poker |