A Bull Call Spread is an options strategy that involves 2 transactions.

A trader initiates a Bull Call Spread by buying a Call option, and conversely selling a Call option in the same expiration month. 

The bought call option, also referred to as the long call, must be at a lower priced strike price than the sold call option, also known as the short call.

By buying +1 call, and selling -1 call at a higher strike price the trader initiates a Debit Spread.  This results in a net debit to the trader’s account and requires a higher trading authority.