Instagram launched a feature they call "Instagram Stories". Theoretically this sounds better than "Snapchat Ripoff". Essentially Instagram has added Snapchat functions to their own platform. Thus you can now use Instagram as you would traditionally or as if it were Snapchat.
Snapchat distinguished itself by becoming home to some of the most boring content on the Internet. Insurance seminars are more exciting than most of the material on Snapchat.
A select group also liked that your posts disappeared after being viewed on Snapchat. This was a big draw for people who posted obscene hand gestures and occasional nudity, but did not like being sued. Of course, then it came out that all of those disappearing posts were being stored on the company's servers. So the company has a different definition of "disappear" than most people do.