According to a new study from Optimal, Twitter brings a smaller but more active audience to brands than Facebook does.

The social advertising and analytics startup looked at data from 4,330 brands, representing a total of 3.49 billion Facebook Likes and 595 million Twitter followers. Last week, those brands added 18.5 million new Likes and 4.5 million new followers. Based on percentage, the average following grew 55 percent faster on Twitter than Facebook.

Notable brands growing fast on Twitter include Skype, Xbox, and Pepsi. One exception is Facebook-owned Instagram. Although the photo app has five times as many Twitter followers as it does Facebook Likes, it increased its fan count 257 percent more quickly on Facebook than on Twitter.

Optimal also broke down the data by industry. Data revealed that most categories are quickly acquiring more followers on Twitter, with Computer Hardware, Softdrinks, and Entertainment Venues leading the way. Only four categories (Books and Magazines, Newspapers, Music and Entertainment Sites/Apps, and Environmental Civic & Social Organizations) showed faster fan growth on Facebook.

While impressive, Twitter’s growth rate won’t surpass that of Facebook — at least not right away — due to the latter’s size. What’s important about this data is that it’s a clear indication that Twitter has become an important channel for many brands to reach fans.

“I think it does show that Twitter is growing and becoming more relevant for brands, too — in a sense ‘catching up’, but also it is different as well,” stated Optimal CEO Rob Leathern. “A smaller but often more active audience.”

That doesn’t mean brands should focus on only one or the other. Balancing your time between social networks should depend on the type of content you’re sharing, and more importantly, where your audience is. If a fashion brand is trying to reach females between the ages of 18 and 35, you might see more growth on Pinterest than Twitter and Facebook combined.

[Via: TechCrunch, Image credit: Timothy J Carroll]