A:AnswerThere is no difference. Sony raised their prices last year from $49.99 to $59.99. Nothing changed with the product. Once all stock has been sold of the lower price, you will only see the $59.99 value. So save a few bucks while you can and get the $49.99 card. That's what I did.
A:AnswerYes. your subscription will stack one year for every card/code you redeem with PSN. So if you buy 2 cards and redeem them you will be good for the next 2 years.
A:AnswerIn my experience, these cards do not expire. Kind of like a gift card. I have saved them for more than a year before using them on my accounts. Once you enter the code on your PlayStation it lasts for exactly 12 months to the day.
A:AnswerPlaystation plus, is a subscription with sony, similar to xbox gold. It's required to have PlayStation plus in order to access online playing on any ps4. Also, it will give you some PlayStation store discounts, and 2 free games each months. Free games are not the best.
PlayStation network cards, is like PlayStation gift card. It has money inside that can be use on the PlayStation store to buy games, rent movies, avatars, buy in game content or games add ons.