The NHL's salary cap is a pair of limits on what a club may spend on its players in a season. The upper limit, usually called the ceiling, is the most a club's cap charges may add up to. The lower limit, the floor, is the least a club must carry. Both are set before each season under the collective bargaining agreement, from the league's hockey-related revenue, which the agreement splits between the clubs and the players. When revenue grows, the limits grow with it.
Every club works inside the same two numbers, whichever city it plays in. That is the point of the system: a club cannot buy its way past the others, and a club that spends to the floor is spending real money on its roster.