Is the £6.99 pages app on Ipad the same as the £14.99 one for Imac?

Is the £6.99 pages app on Ipad the same as the £14.99 one for Imac? It says if you buy the £14.99 app it will work on all your devices, I already have pages and numbers on my Ipad and Iphone and have just bought an Imac, so was wondering if I need to buy the £14.99 one for that or whether I can use the App I already have. Also is there a difference between the two?