"Big Bet" poker usually refers to games in which at least pot-sized bets are permissible, ie. Pot-Limit or No-Limit.
In Fixed-Limit games, the betting rounds will be divided in half regarding rounds using small-bets and big-gets. If there is an odd number or betting rounds, then the extra round will be a big-bet round.
Draw - 2 betting rounds: small-bet pre-draw, big-bet post-draw
Hold 'em, Omaha, Triple-Draw - 4 betting rounds: 1st two rounds small-bet, last two rounds big-bet
Stud - 5 betting rounds: 1st two rounds small-bet, last three rounds big-bet.