Instagram and Snap Inc., the company behind Snapchat, are expected to see massive revenue growth over the next couple years, according to a research note released by Citi Research. If Citi's predictions pan out, Instagram will reach almost $10 billion in revenue by 2019, while the smaller but highly popular Snapchat may hit the $3 billion mark. The reasons for each apps' growth differ, however.

As far as Instagram goes, the company enjoys a massive user base of about 500 million, which is largely behind the anticipated growth. Snapchat, by comparison, boasts a much smaller user base of about 170 million, but those users spend much more time on the app than Instagram's users. According to Citi, Snapchat users are spending more than 30 minutes on the app per day on average.

Both companies are facing an increasing number of competitors, Snapchat in the form of cloned features like Facebook and Instagram Stories, whereas Instagram is competing with the likes of VSCO, EyeEm, and similar platforms. Still, for now it doesn't look like either of these photo sharing behemoths have anything to fear but... well... each other.