Instagram rolled out an update last week that is perhaps the most blatant rip-off of someone else’s work since Robin Thicke’s "Blurred Lines." Its new stories mode is nearly identical to Snapchat’s stories.

The thing is, this is legal and could potentially help Instagram leverage its larger user base to slow Snapchat’s momentum. Fast Company has a helpful explainer on the legal nitty-gritty. Basically, it’s okay to completely rip off another company’s idea as long as you don’t also copy the entire interface or source code.

Just how similar are stories on Snapchat and Instagram? Here’s a list of examples:

Both are called "Stories"

Both allow clips up to 10 seconds in length

Both make stories temporary by removing uploads after 24 hours

Both allow you to select and watch your friends’ stories sequentially

Both allow you to reply to stories with direct messages

Both allow you to add custom text atop your images and video

Both include filters

Both let you draw with a built-in marker

Both include the option to save the media directly to your camera roll

Both display who views your story

There are a few differences, however:

Instagram allows you to "rewind" stories to play back things you may have missed

Instagram has more marker options when it comes to doodling

Instagram lets you post sections of your story as an Instagram post

Instagram doesn’t show you who screenshots your story, but Snapchat does

Geofilters and facial-mapping are still limited to Snapchat

Personally, I think the Instagram interface and design is easier to understand and all-around looks better. Then again, I’ve never loved the look of myself puking rainbows.

Of course, this is just the beginning of this battle. Like some CEO once said, "Competition breeds innovation." Or was it replication?