The general purpose of a pump is to be a pseudo-pancreas and supply a steadier stream of insulin to the body with very little need for repeated SQ shots. There is a huge variety of pumps and modes of delivery out there. You will have to research the particular pump your patient had and what the patient's HCP programmed it to do.
Insulin pens provide a more convenient way to administer insulin. Rather than lugging syringes and drawing up from a vial (a mean feat for someone who has vision or fine motor problems), a person just dials the number of units needed, pops a needle onto the pen and administers. The action of the insulin depends on what kind of insulin is in the pen. I have seen Humalog and regular insulin pens, not so much longer-acting ones. But don't take my word for it. The market for diabetic products is vast.
However, even without that information, you can stress how critical it is to keep blood sugars at a steady level instead of letting it spike and playing this twisted game of catch-up. However, my experience is that long-term noncompliant patients will not be turned by even by the greatest education. The problem is not so much education, really. If that were true, doctors, nurses, people with PhDs etc. would never fall into bad habits, compulsion, addiction, unhealthy thrill-seeking... But they do. Perhaps he is angry at the restraints his diabetes has put on him, maybe he is a punk testing what he can get away with, maybe he eats out of boredom or depression... I don't know.
But what I do know is that my role is a nurse is to support the patient in whatever capacity I can while maintaining my own standards. If this patient chooses not to comply, I will have give him a good, short spiel on where I and his other healthcare providers stand and document fully that I have offered education, patient still refused but I assessed him/her and monitored his condition with as much care as I would if he/she had listened to me. Let him/her know I am here to help, then CYA. Well, CMA (cover my...).