Monte Carlo Simulation,
Complete Enumeration
PokerCruncher does Monte Carlo simulation: it
generates tens of thousands of random hands (often hundreds of thousands) to converge on accurate
odds and stats within seconds. You can set the number of simulations to do, and there's an "Infinite" setting.
However if the scenario is simple enough, PokerCruncher computes the exact odds and stats by doing complete enumeration of the possible cases. For example it does this for postflop scenarios with specific players' cards, which is a common situation (for example the scenario on the Equity/Win/Tie page: 3 players AA vs. KK vs. JT-suited with a specific flop). For such scenarios only the turn and river cards are unspecified, a small number of combinations (on the order of 1000), so PokerCruncher simply enumerates all possible cards for the turn and river to compute the exact answer (and it computes the answer very fast).
Some odds calculators can't compute exact odds and stats even for such simple and common postflop scenarios; they can only do Monte Carlo simulation and can't do complete enumeration.
However if the scenario is simple enough, PokerCruncher computes the exact odds and stats by doing complete enumeration of the possible cases. For example it does this for postflop scenarios with specific players' cards, which is a common situation (for example the scenario on the Equity/Win/Tie page: 3 players AA vs. KK vs. JT-suited with a specific flop). For such scenarios only the turn and river cards are unspecified, a small number of combinations (on the order of 1000), so PokerCruncher simply enumerates all possible cards for the turn and river to compute the exact answer (and it computes the answer very fast).
Other Odds Calculators
Some odds calculators can't compute exact odds and stats even for such simple and common postflop scenarios; they can only do Monte Carlo simulation and can't do complete enumeration.