The basic distinction
A debit spread is opened by paying a net premium. It usually seeks a directional move and has a maximum loss equal to the debit. A credit spread is opened by receiving a net premium and usually seeks the underlying to remain beyond a short strike through expiration.
Both structures use a long option to define risk. The spread width and net debit or credit determine the expiration payoff boundaries.
Reading a simple example
A $10-wide call debit spread bought for $4 risks $400 and can make up to $600 per contract. A $10-wide credit spread sold for $3 can keep $300, while the defined maximum loss is $700 per contract. These figures exclude transaction costs.
The expected direction, breakeven location, and time remaining matter more than whether a strategy has the word debit or credit in its name.
Common planning mistakes
Do not compare premiums without normalizing for width and risk. A larger credit can also mean a larger probability of loss or less room for the underlying to move. Short options can also create assignment and early-exercise considerations before expiration.
Use expected move and risk/reward tools alongside the spread payoff to test whether a scenario fits your risk budget.