The Twitter-owned video sharing service Vine is announcing today that it’s racked up 40 million registered users — a massive increase from the 13 million it announced in early June. But while it’s a big accomplishment for the Vine team, the 40 million number doesn’t tell the whole story.

Instagram is still racking up six times as many tweets

The massive increase coincides with the release of an Android app that in itself was likely responsible for a lot of the surge. Even more importantly, the 40 million figure gives no indication of activity level on the service. In June, MarketingLand looked at Topsy analytics and noted that the number of Vine shares fell dramatically on June 20th, the same day that Instagram released its competing video service. Looking at Topsy today, we see that Instagram is still racking up about six times as many tweets per day as Vine, although there are a lot of factors at play: Instagram offers photo sharing as well as video, and neither figure counts the number of shares that don't make it outside their respective social networks.

Twitter isn't releasing active user figures either, making it difficult to gauge how many of those 40 million accounts are lying dormant. In short, Vine’s announcement is an important milestone for the service, but the battle for video sharing supremacy is far from settled.