To re-iterate, the free upgrades are only available to those who subscribe now, and not for existing Netflix subscribers. Also, the upgrades will be applicable for a period of month. At the end of one month, the subscriber will be asked if he wants to pay extra and continue with the upgraded plan. If not, his plan will revert to the subscription plan he had opted for at the time of buying the subscription.
As for the difference in subscription plans – the Basic plan costs Rs 499 per month and offers Standard Definition (SD) viewing, and on one screen only. The Standard plan costs Rs 649 monthly, and offers high-definition video resolution (HD), and allows simultaneous viewing on two screens. The Premium plan costs Rs 799 monthly, and offers Ultra High-Definition video resolution (UHD) upto 4K resolution, and allows simultaneous viewing on four screens.
The free upgrade offers are a part of a promotional campaign to get more subscribers to buy its higher-priced Standard and Premium plans. Netflix has run similar promotional plans in other countries too. The free offers are designed to give viewers a taste of watching its content at higher resolutions, hoping that they’ll stay on in the higher plans. Of course, if they agree to stay on in the higher-priced plans, they will have to pay the extra cost from there on, since the free upgrades are only for one month.