A vertical spread's value is not just intrinsic — it is driven by delta, gamma, theta, and vega. In a bull call spread, the long lower-strike call has higher delta and gamma than the short higher-strike call, so net delta is positive but capped; net gamma flips sign as spot approaches the short strike.

Time decay can help or hurt depending on moneyness. A debit spread usually benefits from theta when both legs are OTM and the short leg decays faster near expiry.

Delta: net directional exposure, 0 to 1 for a bull call spread.
Gamma: highest near the short strike; can turn net negative.
Theta: debit spreads often positive theta late in life.
Vega: long spread is usually net long vega when strikes are OTM.

Greek	Bull Call Spread	Bear Put Spread
Net Delta	Positive	Negative
Net Gamma	Can be negative near short strike	Can be negative near short strike
Net Theta	Often positive late	Often positive late