With the information you have provided it is a little hard to give a decent answer, but I will give it a crack.
When bulking you should be consuming more cals than what you are burning which means your body will be able to use these extra cals to build muscle
, however, you will also put on some BF, cardio will reduce this but will also reduce the amount of muscle you build due to cardio burning more cals.
I would say that the difference between cutting and bulking is the cardio you are doing and the amount of cals consumed, usually when cutting you would work out the amount of cals burned in a day and consume less cals than burned off therefore, your body will start burning fat for energy.
The weights you are lifting should not change between a bulking or cutting cycle
, this will reduce the impact of losing to much muscle when cutting, provided you diet is squared away.
This is only very basic explanation but you should get the idea.