roughly, and in the context of a car, CCA is the amount of amperes the battery can put out to start the engine. As engines get older they will usually require more.
amperes (the 115 ah) is the amount of storage capacity. so, 115 ah will run a 0.2 amp device (car alarms and all that) for 575 hours with the engine off so it's not charging.
since you usually drive it more often than every 24 days, then you don't need that rating.
Also, it's kinda bollocks as manufacturers use different test periods for ah. So saying 115AH is useless unless they say over how long a duration. Ie it might only be able to do 10 hours, but it can give 11.5 amp over that period.