Here's a quick one - Instagram is starting to let some users post images to Stories from the last week, as opposed to limiting access to content created within the last 24 hours.
Image, and jacket, via Corey Kindberg
In line with Snapchat's functionality, Instagram has thus far focused on keeping Stories as fresh and recent as possible, which is why you're only able to post content to your Story that you've created within the last day. But both Snapchat and Instagram have started to ease that limitation in different ways.
Last year, Snapchat added 'Memories' as a means to include older images in your Stories - though that older content appears with a border to signify that it's not recent.
Snapchat eased this further back in April by removing the borders around Memories content (for images captured within Snapchat), replacing it with a small note on when the image was captured.
On Instagram, they added a live-streaming option to Instagram Stories back in November, and then introduced a way to save that live content indefinitely in March, acknowledging that some people are looking beyond the ephemeral use-case for posts.
In real, functional terms, the option to use content from the last week probably doesn't add a heap, considering there's already a range of simple workarounds to post whatever content you like (slightly edit an image and re-save it to change the time stamp and you can still use it). But still, it'll provide more, immediate content options when composing Instagram Stories - and with the use-cases for Stories expanding, more options can only be a good thing, even if it does take away some of that 'fresh' factor.
Some users have access to the new option, but no word from Instagram yet on a full rollout.