looks like you have 2 months of electricity there.

Dec 13 - Jan 09, then Jan 10 - Feb 08.

Generation is what you pay for power. I'm guessing you have JCP&L generate your power, but you could have a third party if that's something you wanted (or got conned into).
Delivery is what the power company charges to allow your power to come to you over their wires. If you get power generated by others, they still have to bring it to you. So, they break out delivery charges separate from generation.

Your generation is probably dictated by your local tariff. You have a basic amount per KWH for the entire amount, then there is an extra charge for the different levels of service.
This gets complex, so you may want to find their tariff page on their website, or possibly on the State Board of Public Utilities (BPU) site. Make sure you identify which power provider is supplying your generated power.

I don't get why they switch from 3 lines in generation or 3 lines in delivery.
It could be that things changed for the 1st of the year. It could be that they are bad at writing bills.