Seems that there should be an update button on each app instead of an install button which means install the update. Reason? Across the internet, those two terms are distinct, where install means to install a program and update means to update the said program. Anyway, thanks for the clarification!

It is supposed to be an update since you are in the updated section. But I think you're right, it would probably be clearer to new users who have never done so. From memory I thought it was so.