During this year's Made by Google event, the company walked through the plethora of Nest Aware changes relatively quickly, but now more information is surfacing on the revamped subscription service. One of the biggest changes is the removal of 24/7 videotaping which is replaced by event-based recordings in the cheaper $6/month plan.
Previous subscriptions, or 1st gen Nest Aware as Google calls it now, recorded and saved video feeds 24/7. The new Nest Aware only saves events if it detects activity, such as a person walking by or a dog barking. This helps the company save storage and should make it easier for you to sift through the feed. Google is using the freed up space on its servers to expand the availability of recordings to 30 days.
The more expensive Nest Aware Plus ($12/month) still records a 24/7 feed which it keeps for 10 days while holding on to event-based recordings for 60 days. It's still possible to download and share clips with other people on both plans, like you can with 1st gen Nest Aware.
Here's a comparison between 1st gen Nest Aware and the new version: